Use standard Activity as TunerActivity's base.

This is the last activity that depends on SettingsDrawerActivity. This
activity doesn't actually need any functionality from
SettingsDrawerActivity, so we can switch to a standard Activity to
reduce dependency and improve performance.

Bug: 77600770
Test: adb shell am start -a com.android.settings.action.DEMO_MODE
Change-Id: I78ff488be764ae996a96ad4eee05a8c1774a1835