AWS Lambda `_endSpan`/`forceFlush()` can block handler indefinitely

[logaretm]

The vendored AwsLambdaInstrumentation._endSpan calls tracerProvider.forceFlush() without any timeout.

Because _endSpan sits in the promise chain before wrapHandler's flush(2000), a hung forceFlush() blocks the Lambda from ever returning, causing it to sit idle until the Lambda runtime kills it at its configured timeout.

We got the original report on discord.

[linear-code]

JS-2033