test: add karma test showing hydration mismatch when a child component has scoped styles and a custom HTML template

[nrobertdehault]

Details

Add a Karma test reproducing the hydration mismatch described in W-17163956:

• 1 parent component
• 1 child component with the following conditions
  • a scoped stylesheet specified via static stylesheets
  • an imported html template returned by render()

Test fails with the following error:

        Expected [ [ Error: [LWC warn]: Mismatch hydrating element <x-component>: attribute "class" has different values, expected "" but found "lwc-7to96tmocl4-host"
         ], [ Error: [LWC warn]: Hydration completed with errors.
         ] ] to have size 0.

Does this pull request introduce a breaking change?

• 😮‍💨 No, it does not introduce a breaking change.

Does this pull request introduce an observable change?

• 🤞 No, it does not introduce an observable change.

GUS work item

W-17163956

[nolanlawson]

This looks like a duplicate of #4853. This is a great test though and we can definitely use it when we fix that issue. 🙂