Fix crash in brave_ads migration

[jonathanKingston]

Fixes brave/brave-browser#8132

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
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• Verified that these changes pass automated tests (unit, browser, security tests) on
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• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
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• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protection-Mode
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

Upgrade from 1.5.x to 1.6.8, and confirm DB: Error migrating database from v3 to v4 does not appear in the console logs

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[tmancey]

Great work, thank you.

The issue also exists for v1 to v2 so for this PR could you also resolve BundleStateDatabase::MigrateV1toV2 as the final return false; should also be return true;

[jonathanKingston]

Ah I guess I stated at a later migration in the first place to not hit that one. Perhaps that's related to the other crash reports I see in the tracker.

[tmancey]

LGTM++

[tmancey]

@jonathanKingston great work and thank you for taking the time to resolve this issue. As soon as CI passes I will merge to master, keep up the great work!

[jonathanKingston]

@tmancey thanks, I was about to ask what the merge process was :)

[tmancey]

@jonathanKingston CI passed and merged with master. Once again thank you