roachtest: move CheckReplicaDivergenceOnDB to util

[tbg]

This had no business sitting on Cluster.

Release note: None
Release justification: testing code

[cockroach-teamcity]

This change is 

[renatolabs]

Thanks for refactoring! I had seen this code in the past and thought it was weird that it was a method on Cluster.

Since we're looking at this code, I wanted to double check that the comments in that function are still accurate (that we need to set a timeout explicitly, and that the check can fail easily). @tbg would you know if that's still the case?

And a more general question: currently this function is only used by one upgrade test that doesn't use the versionUpgradeTest struct. Would this consistency check be useful in the other upgrade tests as well?

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @srosenberg)

[tbg]

Since we're looking at this code, I wanted to double check that the comments in that function are still accurate (that we need to set a timeout explicitly, and that the check can fail easily). @tbg would you know if that's still the case?

They are, but I have a string of commits that make them more useful: #87378
TFTR!
bors r=renatolabs

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @srosenberg)

[craig]

👎 Rejected by PR status

[tbg]

bors r-

[tbg]

eslint failed on PR CI, but that's not this PR's fault, discussion here.

bors r=renatolabs

[craig]

This PR was included in a batch that successfully built, but then failed to merge into master. It will not be retried.

Additional information:

{"message":"1 review requesting changes by reviewers with write access.","documentation_url":"https://docs.github.com/articles/about-protected-branches"}

[tbg]

bors r=renatolabs

[craig]

Build failed:

• Bazel Essential CI (Cockroach)

[tbg]

bors r=renatolabs

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)