chore: use PerfCounters to replace counters & metrics

[zz-jason]

What's changed and how does it work?

• records counters for each worker thread in PerfContext
• remove old counters and metrics manager
• remove dependency on prometheus-cpp
• providing an example to gather counters in PerfContext

[codecov]

Codecov Report

Attention: Patch coverage is 69.44444% with 11 lines in your changes missing coverage. Please review.

Project coverage is 62.07%. Comparing base (925a074) to head (b802f1b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...nstore/btree/core/PessimisticExclusiveIterator.hpp	40.00%	3 Missing ⚠️
src/btree/TransactionKV.cpp	60.00%	2 Missing ⚠️
src/concurrency/WorkerContext.cpp	50.00%	2 Missing ⚠️
include/leanstore/Exceptions.hpp	0.00%	1 Missing ⚠️
src/buffer-manager/PageEvictor.cpp	0.00%	1 Missing ⚠️
src/leanstore-c/leanstore-c.cpp	0.00%	1 Missing ⚠️
src/telemetry/MetricsHttpExposer.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #129      +/-   ##
==========================================
+ Coverage   56.78%   62.07%   +5.29%     
==========================================
  Files          98       84      -14     
  Lines        7194     6421     -773     
  Branches     3349     2919     -430     
==========================================
- Hits         4085     3986      -99     
+ Misses       2732     2065     -667     
+ Partials      377      370       -7     

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