media: release mediaplayerservice lock while dumping services

Do not hold the global mediaplayerservice lock while dumping services,
as some services may need to add components during this time jsut before
they would be dumped resulting in a dead-lock.

Bug: 191202684
Bug: 230139976
Test: atest MediaRecorderStressTest && adb shell dumpsys media.player
Change-Id: I6b3a96012cb834255b25c5e53d19fce0d9c0dc4e