Added a flag to disable tracing of health check requests

[davide-baldo]

Added the option --otel-disable-healthcheck-tracing to disable health-check requests for both HTTP and GRPC requests.
This PR addresses the issue Allow disabling health check traces

I'm not used to writing Go, so please let me know if there is anything I can do to improve the code or make it more idiomatic.

I've also manually validated the result using a locally deployed Jaeger.

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

[davide-baldo]

I have read the CLA Document and I hereby sign the CLA

[codecov]

Codecov Report

❌ Patch coverage is 49.39759% with 42 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.45%. Comparing base (7b70ff2) to head (8d7a2f4).
⚠️ Report is 23 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/gateway/gateway.go	0.00%	27 Missing ⚠️
pkg/cmd/server/defaults.go	62.17%	12 Missing and 2 partials ⚠️
pkg/cmd/server/server.go	94.74%	1 Missing ⚠️

❌ Your project check has failed because the head coverage (39.45%) is below the target coverage (75.00%). You can increase the head coverage or adjust the target coverage.

❗ There is a different number of reports uploaded between BASE (7b70ff2) and HEAD (8d7a2f4). Click for more details.

HEAD has 43 uploads less than BASE

Flag	BASE (7b70ff2)	HEAD (8d7a2f4)
	54	11

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2494       +/-   ##
===========================================
- Coverage   77.43%   39.45%   -37.97%     
===========================================
  Files         417      376       -41     
  Lines       51071    47129     -3942     
===========================================
- Hits        39541    18592    -20949     
- Misses       9038    26977    +17939     
+ Partials     2492     1560      -932     

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[davide-baldo]

rebased