feat: handle OTEL_TRACES_SAMPLER env var

[jtmalinowski]

Adds support for OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG, in favor of
OTEL_SAMPLING_PROBABILITY.

Which problem is this PR solving?

• Fixes General environment configuration #1675

Short description of the changes

• removes support for OTEL_SAMPLING_PROBABILITY
• adds support for OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG

[codecov]

Codecov Report

Merging #2111 (c049704) into main (09c2aa7) will decrease coverage by 0.08%.
The diff coverage is 89.36%.

@@            Coverage Diff             @@
##             main    #2111      +/-   ##
==========================================
- Coverage   92.73%   92.64%   -0.09%     
==========================================
  Files         138      139       +1     
  Lines        4927     4964      +37     
  Branches     1016     1026      +10     
==========================================
+ Hits         4569     4599      +30     
- Misses        358      365       +7     

Impacted Files	Coverage Δ
packages/opentelemetry-tracing/src/config.ts	86.84% <86.48%> (-13.16%)	⬇️
...ckages/opentelemetry-core/src/utils/environment.ts	95.83% <100.00%> (-4.17%)	⬇️
packages/opentelemetry-core/src/utils/sampling.ts	100.00% <100.00%> (ø)
packages/opentelemetry-tracing/src/utility.ts	100.00% <100.00%> (ø)

[vmarchaud]

overall looks good

[naseemkullah]

lgtm, but could you mark this as breaking and add documentation as how to migrate form OTEL_SAMPLING_PROBABILITY?

If I understand correctly it would be:

old:

OTEL_SAMPLING_PROBABILITY: <SAMPLING_PROBABILITY>

new:

OTEL_TRACES_SAMPLER: parentbased_traceidratio
OTEL_TRACES_SAMPLER_ARG: <SAMPLING_PROBABILITY>

[vmarchaud]

but could you mark this as breaking

I've already added the "breaking" label which should generated the correct entry in the changelog

[jtmalinowski]

@naseemkullah @vmarchaud fixed

[obecny]

generally ok, just one concern with the hardcoded values, please create enum / const for that

[jtmalinowski]

@obecny done, let me know if we need anything else

[obecny]

lgtm, thx for the changes