[fenix] Fix https://github.com/mozilla-mobile/fenix/issues/26362: Use app:lineHeight to support API Level <= 27 (https://github.com/mozilla-mobile/fenix/pull/26364)
* Fix android:lineHeight
Change android:lineHeight to app:lineHeight for incompatibilities at API Level <= 27
* Fix android:lineHeight (Part 2)
Change android:lineHeight to app:lineHeight for fixing incompatibilities in custom_search_engine
* Change android:lineHeight (Part 3)
Change android:lineHeight to app:lineHeight in settings_https_only for incompatibilities at API Level <= 27
* cleanup lint-baseline.xml
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>