fix(pgo): fix the git diff and change the e2e tests

[v1v]

Consume https://github.com/elastic/apm-managed-service/tree/main/pgo for running the e2e tests

In addition, it fixes the issue when git diff cannot track a new file:

       -N, --intent-to-add
           Record only the fact that the path will be added later. An entry for the path is placed in the index with no content. This is useful for, among other things, showing the unstaged content of such
           files with git diff and committing them with git commit -a.

Notifies #83

Version 0.1.0 does not work when the default.pgo file does not exist in the target repository:

----
No change detected
✔ - ran shell command "tar -xzf /home/runner/work/apm-ingest-service/apm-ingest-service/pgo.tgz && git --no-pager diff"
ACTIONS
========
automation: update PGO
  => [Automation] Update default.pgo
No follow up action needed
=============================
SUMMARY:
✔ automation: update PGO:
	Source:
		✔ [pgo-file] 
		✔ [pull_request] 
		✔ [sha] 
	Target:
		✔ [pgo] PGO file 9c996d1116376a7051d8eb427ae28895c3b4baee

See https://github.com/elastic/apm-ingest-service/actions/runs/13496471932/job/37704792105#step:5:154