Fix Monitor Plugin `getTransactionStats`

[bobanm]

What was the problem?

This PR resolves #9082

How was it solved?

Changed used endpoint from app_getConnectedPeers into network_getConnectedPeers

How was it tested?

When invoking monitor_getTransactionStats endpoint, the result now includes connectedPeers property, e.g:

{
  "transactions": {},
  "connectedPeers": 0,
  "averageReceivedTransactions": 0
}

[codecov[bot]]

Codecov Report

Merging #9091 (c1c1b1c) into release/6.0.0 (c9c1ecc) will increase coverage by 0.00%. Report is 2 commits behind head on release/6.0.0. The diff coverage is 100.00%.

:exclamation: Current head c1c1b1c differs from pull request most recent head d3ab90b. Consider uploading reports for the commit d3ab90b to get more accurate results

@@              Coverage Diff               @@
##           release/6.0.0    #9091   +/-   ##
==============================================
  Coverage          83.47%   83.47%           
==============================================
  Files                604      604           
  Lines              22803    22807    +4     
  Branches            3364     3365    +1     
==============================================
+ Hits               19035    19039    +4     
  Misses              3768     3768           

Files	Coverage Δ
...ork-monitor-plugin/src/controllers/transactions.ts	22.22% <ø> (ø)
framework/src/engine/bft/method.ts	89.23% <100.00%> (+0.34%)	:arrow_up:
framework/src/engine/bft/module.ts	100.00% <100.00%> (ø)
framework/src/engine/consensus/consensus.ts	82.68% <100.00%> (ø)
framework/src/engine/generator/generator.ts	81.88% <ø> (ø)
framework/src/schema/application_config_schema.ts	100.00% <ø> (ø)
framework/src/testing/fixtures/config.ts	41.66% <ø> (ø)
framework/src/types.ts	100.00% <ø> (ø)