chore: Remove unused imports from template

[dpogue]

Platforms affected

iOS

Motivation and Context

This work was missed in https://github.com/apache/cordova-ios/pull/1161 and is now causing errors.

Description

Removed unused headers from the project template.

Testing

Unit tests pass (although they also didn't catch this being an error last time)

Checklist

• [x] I've run the tests to see all new and existing tests pass

[dpogue]

Does the command sequence described in #1172 work for you with this change?

Just tried it, and yes it does