chore(systemtests): Remove testutil dependency (backport #21995)

[mergify]

Description

Remove testutil dependency and minor updates.

---

Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• included the correct type prefix in the PR title, you can find examples of the prefixes below:

• confirmed ! in the type prefix if API or client breaking change

• targeted the correct branch (see PR Targeting)

• provided a link to the relevant issue or specification

• reviewed "Files changed" and left comments if necessary

• included the necessary unit and integration tests

• added a changelog entry to CHANGELOG.md

• updated the relevant documentation or specification, including comments for documenting Go code

• confirmed all CI checks have passed

Reviewers Checklist

All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.

Please see Pull Request Reviewer section in the contributing guide for more information on how to review a pull request.

I have...

• confirmed the correct type prefix in the PR title
• confirmed all author checklist items have been addressed
• reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

Summary by CodeRabbit

• New Features

  • Enhanced testing for bank transactions, including improved error handling and validation for various scenarios.
  • Introduced utility functions for file operations, simplifying error management in tests.
  • Added functionality for managing blockchain snapshots and pruning operations in tests.
  • Transitioned testing framework from GRPC to REST, improving alignment with current API structures.

• Bug Fixes

  • Corrected balance comparison logic in transaction tests for clarity and accuracy.

• Documentation

  • Updated comments and formatting for better readability and maintainability in test files.

---

This is an automatic backport of pull request #21995 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 72f7716 has failed:

On branch mergify/bp/release/v0.52.x/pr-21995
Your branch is up to date with 'origin/release/v0.52.x'.

You are currently cherry-picking commit 72f771638.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   tests/systemtests/authz_test.go
	modified:   tests/systemtests/bank_test.go
	modified:   tests/systemtests/fraud_test.go
	modified:   tests/systemtests/gov_test.go
	new file:   tests/systemtests/io_utils.go
	modified:   tests/systemtests/rest_cli.go
	modified:   tests/systemtests/system.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   tests/systemtests/bankv2_test.go
	deleted by us:   tests/systemtests/cometbft_client_test.go
	deleted by us:   tests/systemtests/snapshots_test.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[coderabbitai]

Important

Review skipped

Bot user detected.

To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

---

🪧 Tips

Chat

There are 3 ways to chat with CodeRabbit:

• Review comments: Directly reply to a review comment made by CodeRabbit. Example:
  • I pushed a fix in commit <commit_id>, please review it.
  • Generate unit testing code for this file.
  • Open a follow-up GitHub issue for this discussion.
• Files and specific lines of code (under the "Files changed" tab): Tag @coderabbitai in a new review comment at the desired location with your query. Examples:
  • @coderabbitai generate unit testing code for this file.
  • @coderabbitai modularize this function.
• PR comments: Tag @coderabbitai in a new PR comment to ask questions about the PR branch. For the best results, please provide a very specific query, as very limited context is provided in this mode. Examples:
  • @coderabbitai gather interesting stats about this repository and render them as a table. Additionally, render a pie chart showing the language distribution in the codebase.
  • @coderabbitai read src/utils.ts and generate unit testing code.
  • @coderabbitai read the files in the src/scheduler package and generate a class diagram using mermaid and a README in the markdown format.
  • @coderabbitai help me debug CodeRabbit configuration file.

Note: Be mindful of the bot's finite context window. It's strongly recommended to break down tasks such as reading entire modules into smaller chunks. For a focused discussion, use review comments to chat about specific files and their changes, instead of using the PR comments.

CodeRabbit Commands (Invoked using PR comments)

• @coderabbitai pause to pause the reviews on a PR.
• @coderabbitai resume to resume the paused reviews.
• @coderabbitai review to trigger an incremental review. This is useful when automatic reviews are disabled for the repository.
• @coderabbitai full review to do a full review from scratch and review all the files again.
• @coderabbitai summary to regenerate the summary of the PR.
• @coderabbitai resolve resolve all the CodeRabbit review comments.
• @coderabbitai configuration to show the current CodeRabbit configuration for the repository.
• @coderabbitai help to get help.

Other keywords and placeholders

• Add @coderabbitai ignore anywhere in the PR description to prevent this PR from being reviewed.
• Add @coderabbitai summary to generate the high-level summary at a specific location in the PR description.
• Add @coderabbitai anywhere in the PR title to generate the title automatically.

Documentation and Community

• Visit our Documentation for detailed information on how to use CodeRabbit.
• Join our Discord Community to get help, request features, and share feedback.
• Follow us on X/Twitter for updates and announcements.

[julienrbrt]

blocked on this backport: #21986