exp/tools/dump-ledger-state: Remove dump-ledger-state script

[tamirms]

PR Checklist

PR Structure

• This PR has reasonably narrow scope (if not, break it down into smaller PRs).
• This PR avoids mixing refactoring changes with feature changes (split into two PRs
  otherwise).
• This PR's title starts with name of package that is most changed in the PR, ex.
  services/friendbot, or all or doc if the changes are broad or impact many
  packages.

Thoroughness

• This PR adds tests for the most critical parts of the new functionality or fixes.
• I've updated any docs (developer docs, .md
  files, etc... affected by this change). Take a look in the docs folder for a given service,
  like this one.

Release planning

• I've updated the relevant CHANGELOG (here for Horizon) if
  needed with deprecations, added features, breaking changes, and DB schema changes.
• I've decided if this PR requires a new major/minor version according to
  semver, or if it's mainly a patch change. The PR is targeted at the next
  release branch if it's not a patch change.

What

Remove dump-ledger-state script and the CI job which publishes the stellar/ledger-state-diff docker container.

Why

The dump-ledger-state script relies on being able to query ledger entries from the stellar-core SQL db. However, stellar-core will no longer store ledger entries in its SQL db. Instead, stellar-core will maintain ledger entries in the bucketlistdb. The functionality which is tested in the dump-ledger-state script mostly overlaps with state verification, so it's not really worth updating the script so that it can extract ledger entries from bucketlistdb instead of the stellar-core SQL db.

Known limitations

[N/A]