Testing: Update no gpu test to check otel config

[LujieDuan]

Description

Update TestNoNvmlOtelReceiverWithoutGpu to check the generated otel config and assert that nvml receiver is not in the generated config when the VM has no GPU.

Related issue

b/341109955

How has this been tested?

Integration test passing.
Tested locally to make sure the test reports correct error when the generated otel config is not presented in the VM.

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]

Added two optional comments, aside from that LGTM!