Add aws.pulse.over.midlina attribute for lambda spans

[mxiamxia]

Description of changes:

Add aws.pulse.over.midlina for lambda spans when AppSignals is enabled, so server side can use it to determine whether it should generate EMF metrics

2024-09-27T15:19:32.789-07:00 | 'faas.name': 'aws-opentelemetry-distro-nodejs', | 2024/09/27/[$LATEST]af2cea6e28a94c24aa098ed39567d85b
-- | -- | --
  | 2024-09-27T15:19:32.789-07:00 | 'faas.version': '$LATEST', | 2024/09/27/[$LATEST]af2cea6e28a94c24aa098ed39567d85b
  | 2024-09-27T15:19:32.789-07:00 | 'faas.instance': '2024/09/27/[$LATEST]af2cea6e28a94c24aa098ed39567d85b', | 2024/09/27/[$LATEST]af2cea6e28a94c24aa098ed39567d85b
  | 2024-09-27T15:19:32.789-07:00 | 'aws.log.group.names': '/aws/lambda/aws-opentelemetry-distro-nodejs', | 2024/09/27/[$LATEST]af2cea6e28a94c24aa098ed39567d85b
  | 2024-09-27T15:19:32.789-07:00 | 'aws.pulse.over.midlina': 'true'

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.