Cache SHOW_MEDIA_ON_QUICK_SETTINGS

Store value of SHOW_MEDIA_ON_QUICK_SETTINGS the first time it is queried
to avoid binder calls on critical path. SHOW_MEDIA_ON_QUICK_SETTINGS
should not change at runtime.

Test: Ensure Settings.Global.getInt is not called during Lockscreen PIN
      disappear CUJ
Test: adb shell settings put global qs_media_controls 1 && \
        atest SystemUITests:NotificationSectionsFeatureManagerTest
Test: adb shell settings put global qs_media_controls 0 && \
        atest SystemUITests:MediaResumeListenerTest
Bug: 230620480
Change-Id: Ie3264573071b6daa1cc7393d99aad5359bc2fd1a