v1.18: RPC: fix numNonVoteTransactions in getPerformanceSamples (backport of #1189)

[mergify]

Problem

The value numNonVoteTransactions returned in the RPC getPerformanceSamples endpoint was actually reporting the number of successful non vote transactions that were executed. That field is documented in the RPC docs with the following statement:

To get a number of voting transactions compute numTransactions - numNonVoteTransaction"

But before this fix, numTransactions - numNonVoteTransaction is actually computing the number of vote transactions + errored non-vote transactions.

Summary of Changes

• Increment executed_non_vote_transactions_count whether the non-vote tx failed or succeeded. This value will get fixed on restart since we don't persist the value in snapshots

Fixes #

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This is an automatic backport of pull request #1189 done by [Mergify](https://mergify.com).

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.6%. Comparing base (a73b6cb) to head (2eacc4f).

Additional details and impacted files

@@            Coverage Diff            @@
##            v1.18    #1208     +/-   ##
=========================================
- Coverage    81.6%    81.6%   -0.1%     
=========================================
  Files         827      827             
  Lines      225352   225352             
=========================================
- Hits       184043   184036      -7     
- Misses      41309    41316      +7     

[CriesofCarrots]

Low-risk change that fixes a bug and is isolated to the SamplePerformanceService and the related RPC call; I'm okay with the backport.