Move resource tag of play pause button to the icon inside

Flag: com.android.systemui.media_controls_in_compose
Bug: 434232042
Test: atest PlatformScenarioTests:android.platform.test.scenario.sysui.media.QSMediaControllerPlayAndPause
Change-Id: I492be69ee89451ae3be0b210f8d8ead33fb0a759