Bump errorprone to 2.38.0

[CRogers]

Before this PR

Error-prone 2.38.0 has ABI breaks since 2.31.0. Internally, open source libraries that depend on error-prone-annotations are bumping up error-prone to 2.38.0, and these errors are manifesting. We should be on latest.

We upgraded baseline here: palantir/gradle-baseline#3121

After this PR

==COMMIT_MSG==
Bump errorprone to 2.38.0
==COMMIT_MSG==

Most of the test changes are just tidy up to get rid of the System.outs that errorprone now complains about.

Possible downsides?

This repo has is stuck on a really old version of baseline, because the moment baseline started applying suppressible-error-prone, there is this weird self-referential error as Gradle tries to replace the suppressible-error-prone module with the local project (and requiring it's own jar before the :

> Could not resolve all files for configuration ':suppressible-error-prone:annotationProcessor'.
  > Failed to transform suppressible-error-prone-2.9.0-24-g6b3d671.dirty.jar (project :suppressible-error-prone) to match attributes {artifactType=jar, com.palantir.suppressible-error-prone.suppressible=true, org.gradle.category=library, org.gradle.dependency.bundling=external, org.gradle.jvm.version=17, org.gradle.libraryelements=jar, org.gradle.usage=java-runtime}.
    > Execution failed for ModifyErrorProneCheckApi: /Users/callumr/git/suppressible-error-prone/suppressible-error-prone/build/libs/suppressible-error-prone-2.9.0-24-g6b3d671.dirty.jar.
      > Transform output /Users/callumr/git/suppressible-error-prone/suppressible-error-prone/build/libs/suppressible-error-prone-2.9.0-24-g6b3d671.dirty.jar must exist.

To work around this, I've not upgraded the gradle plugin but have upgraded the baseline-error-prone jar that contains the error prone checks. We need this upgraded as these baseline checks were broken by upgrading error-prone.

I'm working on a long lived fix.

[changelog-app]

Generate changelog in changelog/@unreleased

Type (Select exactly one)

• Feature (Adding new functionality)
• Improvement (Improving existing functionality)
• Fix (Fixing an issue with existing functionality)
• Break (Creating a new major version by breaking public APIs)
• Deprecation (Removing functionality in a non-breaking way)
• Migration (Automatically moving data/functionality to a new system)

Description

Bump errorprone to 2.38.0

Check the box to generate changelog(s)

• Generate changelog entry

[stale]

This PR has been automatically marked as stale because it has not been touched in the last 14 days. If you'd like to keep it open, please leave a comment or add the 'long-lived' label, otherwise it'll be closed in 7 days.

[CRogers]

Superseded by #18