[component] Remove incorrect comment on Factory interface

[TylerHelmuth]

Description

Removes an incorrect comment from the component.Factory interface.

This comment was added via #4338 when the extension/receiver/processor/exporter factory types all still lived in component. Since the factories have been moved to other modules, component.Factory needs to be implementable.

The specific extension/receiver/processor/exporter factory types are unimplementable since they are defined in internal packages.

Link to tracking issue

Related to #6506

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.03%. Comparing base (6329c24) to head (d42168d).
Report is 16 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11017      +/-   ##
==========================================
+ Coverage   91.75%   92.03%   +0.27%     
==========================================
  Files         412      412              
  Lines       19344    19313      -31     
==========================================
+ Hits        17750    17774      +24     
+ Misses       1232     1185      -47     
+ Partials      362      354       -8     

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[mx-psi]

I am in favor of this, while I believe it is technically feasible to make the interface sealed, I feel like the change could be a ~biggish refactor with no clear benefit