Do not call retrieveMedia() if it is already done

Bug: 77304533
Test: succeeded building and tested aosp Music app with 60 mp3 files.
Change-Id: I69cdef1f11cf36502dffd0be41d62711adfd49d4
Merged-In: I69cdef1f11cf36502dffd0be41d62711adfd49d4
(cherry picked from commit 55e09c4068e9339986bf41890f27753b5a3ab1c2)
1 file changed