Add resource with pid to OTEL metrics

[varmar05]

This is to avoid multiple workers overwriting the same metrics in prometheus.

[coveralls]

Coverage Report for CI Build 28501099117

Coverage decreased (-0.03%) to 92.129%

Details

• Coverage decreased (-0.03%) from the base build.
• Patch coverage: 6 uncovered changes across 1 file (0 of 6 lines covered, 0.0%).
• 1 coverage regression across 1 file.

Uncovered Changes

File	Changed	Covered	%
server/mergin/otel/instrument.py	6	0	0.0%

Coverage Regressions

1 previously-covered line in 1 file lost coverage.

File	Lines Losing Coverage	Coverage
server/mergin/otel/instrument.py	1	0.0%

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Coverage Stats

Relevant Lines:	10024
Covered Lines:	9235
Line Coverage:	92.13%
Coverage Strength:	0.92 hits per line

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💛 - Coveralls