[mdatagen] fix generated comp test for extensions and unused imports in templates

[adrielp]

Description

When upgrading beyond v0.101.0 of mdatagen I ran into issues upgrading when running golanglint-ci because of unused imports. Namely, in component_tests the component was removed from this commit which was not caught by tests (it appears we only test receiver components & not others). The logic that generates tests for extensions, where I caught this error, ends up with a generated_component_test that does not use component in the package at all. I would've thought the contrib repo would've detected this issue since they also use mdatagen and there are extensions there + golangci-lint. I haven't dug into the why it wasn't caught there yet.

This is just a quick fix for extensions. I suspect this issue may pop up in other components as time goes on. Long term is more tests for other components.

Testing

I ran this locally against my own repo where the issue originally showed & ensured the value would be templated out appropriately.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 92.41%. Comparing base (fead8fc) to head (5b29e5a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10477   +/-   ##
=======================================
  Coverage   92.41%   92.41%           
=======================================
  Files         393      393           
  Lines       18605    18605           
=======================================
  Hits        17194    17194           
  Misses       1056     1056           
  Partials      355      355           

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