[android] Delete unused media

...d/fenix/app/src/beta/ic_launcher_monochrome-playstore.png

...g/mozilla/fenix/experiments/view/ResearchSurfaceSurvey.kt

...ava/org/mozilla/fenix/microsurvey/ui/MicroSurveyHeader.kt

.../mozilla/fenix/microsurvey/ui/MicrosurveyRequestPrompt.kt

...p/src/main/res/drawable-night/ic_logo_wordmark_normal.xml

...le/android/fenix/app/src/main/res/drawable/ic_firefox.xml

...enix/app/src/main/res/drawable/ic_launcher_monochrome.xml

mobile/android/fenix/app/src/main/res/drawable/ic_scan.xml

...d/fenix/app/src/main/res/layout/fragment_turn_on_sync.xml

...ndroid/fenix/app/src/main/res/values-night-v27/styles.xml

...le/android/fenix/app/src/main/res/values-night/styles.xml

mobile/android/fenix/app/src/main/res/values/styles.xml

...enix/app/src/nightly/ic_launcher_monochrome-playstore.png

...enix/app/src/release/ic_launcher_monochrome-playstore.png