fix(android): only the active player may stop the shared MediaPlaybackService

[tvanlaerhoven]

Summary

Fixes #918. Split out from the review discussion on #917 (#917 (comment)); not part of the 11.7.0 release.

All player contexts with background audio bind to one shared MediaPlaybackService. destroy() already gates the media session connector teardown on ownsMediaSession(), but the service stop one line above it was unconditional. Destroying an inactive player therefore removed the foreground notification and stopped the service of the player that was still active. applyBackgroundPlaybackConfig() (disabling background audio at runtime) had the same unconditional call.

// destroy()
if (BuildConfig.USE_PLAYBACK_SERVICE) {
-  binder?.stopForegroundService()
+  if (ownedMediaSession) {
+    binder?.stopForegroundService()
+  }
   unbindMediaPlaybackService()
}

// applyBackgroundPlaybackConfig(), disabling branch
-  binder?.stopForegroundService()
+  if (ownsMediaSession()) {
+    binder?.stopForegroundService()
+  }
   unbindMediaPlaybackService()

Unbinding stays unconditional: when the last client unbinds, Android destroys the service and onDestroy() cleans up the session. ownsMediaSession() returns true when binder == null, so single-player behaviour is unchanged.

Not done here (optional hardening from the issue): making MediaPlaybackBinder.stopForegroundService() take the calling context and ignore non-owners.

Link to Devin session: https://dolby.devinenterprise.com/sessions/56f1f4577f7044829520dd18f54efc76
Open in Devin Desktop: https://dolby.devinenterprise.com/desktop/session/56f1f4577f7044829520dd18f54efc76?variant=devin
Requested by: @tvanlaerhoven

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✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.