Revert "AML: Make MediaSessionManager.createSession() as @SystemApi"

This reverts commit 0852ebab418adcf4abc661d4b495c74c1069293c.

Reason for revert: Return and parameter types of added SystemApi are not themselves part of the API.

Bug: 119749862
Change-Id: I9f89abc25d2f3f6cff60c2465fca8e471e7f1f2a
2 files changed