Enable persistent logs

[quentinmit]

Description

Using a file_storage for persistent logs allows us to survive network outages by storing in-flight logs on disk.

Also, because googlecloudexporter retries happen inside gRPC, we need to bump the RPC timeout up to 3600s or else the logs and just dropped at 60s anyway.

Related issue

b/491197162

How has this been tested?

Manually tested the generated config on a test VM; will also check the integration tests on this PR.

Checklist:

• Unit tests
  • Unit tests do not apply.
  • Unit tests have been added/modified and passed for this PR.
• Integration tests
  • Integration tests do not apply.
  • Integration tests have been added/modified and passed for this PR.
• Documentation
  • This PR introduces no user visible changes.
  • This PR introduces user visible changes and the corresponding documentation change has been made.
• Minor version bump
  • This PR introduces no new features.
  • This PR introduces new features, and there is a separate PR to bump the minor version since the last release already.
  • This PR bumps the version.

[franciscovalentecastro]

LGTM!

As a suggestion (which may not be worth it) we could integrate the Otel Logging persistence into the existing TestBufferLimitSizeOpsAgent test which verifies the size of fluent-bit persistence.