fix: AWS Lambda collector.

[pvital]

Fix initialization of spans and metrics collectors for the AWS Lambda Collector to prevent breaking while reporting spans, like the error below:

[INFO]	2026-09-21T12:06:04.711Z		Stan is on the AWS Lambda scene. Starting Instana instrumentation version: 3.19.0
[DEBUG]	2026-09-21T12:06:04.711Z		Runtime environment: Machine: x86_64, System: Linux, Python version: 3.11.16
[DEBUG]	2026-09-21T12:06:04.711Z		Loading AWS Lambda Collector
[DEBUG]	2026-09-21T12:06:04.711Z		BaseCollector.start: launching collection thread
[DEBUG]	2026-09-21T12:06:04.712Z		report_data_payload: connection error (<class 'TypeError'>)
[DEBUG]	2026-09-21T12:06:04.765Z		Instrumenting asyncio
[DEBUG]	2026-09-21T12:06:04.782Z		Instrumenting logging
[DEBUG]	2026-09-21T12:06:04.798Z		Instrumenting urllib3
[DEBUG]	2026-09-21T12:06:04.803Z		Instrumenting gevent: gevent not detected or loaded.  Nothing done.
[DEBUG]	2026-09-21T12:06:04.808Z		Instrumenting DynamoDB
[DEBUG]	2026-09-21T12:06:04.930Z		Instrumenting s3
[DEBUG]	2026-09-21T12:06:04.936Z		Instrumenting AWS Lambda handler (lambda_function.lambda_handler)
START RequestId: 64a581fc-7a04-49e7-b932-e71ea604942f Version: $LATEST
[DEBUG]	2026-09-21T12:06:04.961Z	64a581fc-7a04-49e7-b932-e71ea604942f	Detected as Unknown Trigger: {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'}
[DEBUG]	2026-09-21T12:06:06.596Z	64a581fc-7a04-49e7-b932-e71ea604942f	Collector.shutdown: Reporting final data.
[DEBUG]	2026-09-21T12:06:06.597Z	64a581fc-7a04-49e7-b932-e71ea604942f	report_data_payload: connection error (<class 'TypeError'>)
END RequestId: 64a581fc-7a04-49e7-b932-e71ea604942f
REPORT RequestId: 64a581fc-7a04-49e7-b932-e71ea604942f	Duration: 1675.09 ms	Billed Duration: 2486 ms	Memory Size: 128 MB	Max Memory Used: 86 MB	Init Duration: 810.79 ms

[GSVarsha]

Looks good to me!