fix(compiler): Prevent `extTransformsPlugin` from outputting collection dependency css

[George-Payne]

Pull request checklist

Please check if your PR fulfills the following requirements:

• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been reviewed and added / updated if needed (for bug fixes / features)
• [x] Build (npm run build) was run locally and any changes were pushed
• [x] Unit tests (npm test) were run locally and passed
• [x] E2E Tests (npm run test.karma.prod) were run locally and passed
• [x] Prettier (npm run prettier) was run locally and passed

Pull request type

Please check the type of change your PR introduces:

• [x] Bugfix
• [ ] Feature
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes
• [ ] Other (please describe):

What is the current behavior?

GitHub Issue Number: #3305

What is the new behavior?

extTransformsPlugin will no longer output collection dependency css when building collection files.

Does this introduce a breaking change?

• [ ] Yes
• [x] No

Testing

Linked build of stencil to reproduction lib and rebuilt lib.

Other information

[mikaelkaron]

patch works here.