v3.1: runtime: Add test for epoch boundary (backport of #8838)

[mergify]

Add test that ensures correct values in Bank and PartitionedRewardsCalculation after crossing epoch boundary.

---

This is an automatic backport of pull request #8838 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 30d8afd has failed:

On branch mergify/bp/v3.1/pr-8838
Your branch is up to date with 'origin/v3.1'.

You are currently cherry-picking commit 30d8afd32.
  (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:   runtime/src/bank/partitioned_epoch_rewards/mod.rs

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   runtime/src/bank/partitioned_epoch_rewards/calculation.rs

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

[t-nelson]

@vadorovsky can you rebase when you fix conflicts here? need to pickup the version bump commit to pass sanity

[t-nelson]

@vadorovsky ping

[vadorovsky]

Sorry for late reaction, done.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 99.42529% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 83.2%. Comparing base (8887656) to head (f1e6ae3).

Additional details and impacted files

@@           Coverage Diff            @@
##             v3.1    #9149    +/-   ##
========================================
  Coverage    83.2%    83.2%            
========================================
  Files         865      865            
  Lines      375625   375787   +162     
========================================
+ Hits       312710   312846   +136     
- Misses      62915    62941    +26     

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[t-nelson]

derp needs conflict resolution again

[vadorovsky]

green again

[t-nelson]

@HaoranYi can you give sme review for this bp?