Enable OTLP collector sidecar for non-Python agents (.NET, Java, TypeScript) in AgentCore Runtime

[philasmar]

Description

The AgentCore Runtime currently only starts the ADOT collector sidecar (listening on localhost:4318) when it detects opentelemetry-instrument in the container entrypoint — which is Python-specific. For .NET (and Java/TypeScript) agents that use the OpenTelemetry SDK directly to export OTLP over HTTP/Protobuf to localhost:4318, nothing is listening on that port, so telemetry is silently dropped.

Current behavior

• Python agents: Runtime detects opentelemetry-instrument in entrypoint → starts ADOT collector sidecar on localhost:4318 → telemetry flows to CloudWatch/X-Ray ✓
• .NET/Java/TS agents: Runtime does not start the sidecar → localhost:4318 is unreachable → OTLP export silently fails → no telemetry in CloudWatch ✗

Expected behavior

The ADOT collector sidecar should start for all agent containers regardless of language/entrypoint, accepting OTLP HTTP/Protobuf on localhost:4318 and forwarding to CloudWatch (traces → X-Ray, metrics → CloudWatch Metrics, logs → CloudWatch Logs).

Acceptance Criteria

• The ADOT collector sidecar starts on localhost:4318 (HTTP/Protobuf) for containers with any entrypoint, not just those using opentelemetry-instrument
• .NET agents sending OTLP HTTP/Protobuf to localhost:4318 have their traces appear in X-Ray via CloudWatch Transaction Search
• .NET agents sending OTLP HTTP/Protobuf to localhost:4318 have their metrics appear in CloudWatch Metrics
• .NET agents sending OTLP HTTP/Protobuf to localhost:4318 have their structured logs appear in CloudWatch Logs
• No code changes are required in the agent application — the standard OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 convention works out of the box
• The behavior is consistent with what Python agents already get via the existing sidecar

Additional Context

No response