otel exporter for http collector endpoint

[hamersaw]

Tracking issue

NA

Why are the changes needed?

Currently using the otel integration requires deploying an otel collector compatible endpoint in the benchmarking environment. Managing this deployment (ie. deployment, endpoint access, etc) can add unnecessary difficulty to ad-hoc benchmarking.

What changes were proposed in this pull request?

For quick benchmarking this PR enables the file exporter to write json marhsalled protobufs to satisfy the otel http collector endpoint. The flow here is as follows:

1. enable otel_collector file exporter in propeller
2. execute workflow(s)
3. download exported file
4. import into jaeger (or other otel collector compatible framework)
5. profit

How was this patch tested?

local, cloud, etc

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

NA

Docs link

NA

[codecov]

Codecov Report

Attention: 379 lines in your changes are missing coverage. Please review.

Comparison is base (75c2b08) 58.15% compared to head (994a946) 57.74%.
Report is 1 commits behind head on master.

Files	Patch %	Lines
flytestdlib/otelutils/span.go	0.00%	267 Missing ⚠️
flytestdlib/otelutils/file_exporter.go	6.60%	99 Missing ⚠️
flytestdlib/otelutils/factory.go	40.90%	11 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4650      +/-   ##
==========================================
- Coverage   58.15%   57.74%   -0.41%     
==========================================
  Files         626      628       +2     
  Lines       53786    54169     +383     
==========================================
+ Hits        31277    31281       +4     
- Misses      20001    20380     +379     
  Partials     2508     2508              

Flag	Coverage Δ
unittests	57.74% <4.29%> (-0.41%)	⬇️

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