Improve CI TPS metering input

[janezpodhostnik]

closes: https://github.com/onflow/flow-go/issues/5490

CI TPS metering can now optionally take load parameters from a yaml file.

This PR also contains a small cleanup of unused TPS monitor features.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 55.70%. Comparing base (5429925) to head (99362c4).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5548      +/-   ##
==========================================
+ Coverage   55.65%   55.70%   +0.05%     
==========================================
  Files        1041     1033       -8     
  Lines      101935   101503     -432     
==========================================
- Hits        56729    56544     -185     
+ Misses      40846    40609     -237     
+ Partials     4360     4350      -10     

Flag	Coverage Δ
unittests	55.70% <ø> (+0.05%)	:arrow_up:

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