As part of the V2 architecture changes the agent specification file format is being redesigned to remove automatic configuration transformations like inject_stream_processor.

Both filebeat and metricbeat currently rely on a variety of configuration file transformations when run under agent which must be removed:

• https://github.com/elastic/elastic-agent/blob/main/internal/spec/filebeat.yml
• https://github.com/elastic/elastic-agent/blob/main/internal/spec/metricbeat.yml

The scope of this issue is to move the logic for each of these configuration transformations into the beat itself when it detects it is being run under agent (for example, seeing the -management.enabled flag on the command line).

Relates To:

• [Meta] Remove Elastic Agent V1 control protocol elastic-agent-client#32
• PR including reference V2 specification files: [v2] Add v2 component specification and validation. elastic-agent#502
• Inject Beat gRPC stream identifiers without relying on agent specification file transformations #33135

This task is considered complete when a test exists proving that filebeat and metricbeat behave correctly when started using their V2 specification file. This includes but is not limited to testing that:

• There were no unexpected changes to the format of published documents.
• Each available input defined in the specification file can be started.
• Policy changes adding processors, inputs, or new output configurations take effect as expected.