Fix metrics temporality env var interpolation in docker-compose

[aknuds1]

Summary

Fixes #2884

The docker-compose.yml uses the syntax - OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE which passes the variable from the shell environment, not from the .env file. When the shell doesn't have this variable set, Docker Compose doesn't apply the .env value - instead, the value baked into the container images (delta) takes precedence. See reference on how environment variable interpolation works with .env files.

This causes Prometheus to reject metrics with "invalid temporality and type combination" errors, affecting HTTP/RPC server metrics from most services.

Changes

Changed all occurrences from:

- OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE

To explicit interpolation:

- OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE=${OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE}

Test plan

1. make start
2. Verify docker exec cart env | grep TEMPORALITY shows cumulative
3. Verify docker logs prometheus 2>&1 | grep "invalid temporality" shows no errors
4. Check APM dashboard shows metrics for cart, checkout, ad, etc.

[julianocosta89]

This change shouldn't be necessary.
All the env vars come from the .env file, and when the env var has the same name as whatever is set in the .env file, the value from the .env file is used.

@aknuds1 Could you elaborate further on the issue?
Most OTLP endpoints and all resource attributes are being set without ${value} being explicitly set.
Everything comes from .env file.

[aknuds1]

I will try again tomorrow.

[aknuds1]

@julianocosta89 I tried to reproduce yesterday's problem (delta temporality being configured in the demo stack) this morning, but couldn't. I've inferred that the probable cause was OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE=delta being exported in my shell for some reason unknown to me (I didn't set it knowingly). I got confused by the Docker Compose documentation making it look like there's a behavioral difference between the syntaxes. Sorry for the noise!