Update media2 session references to media3 in framework docs

The androidx.media2 library is deprecated, and the source has been deleted.

Bug: 324249307
Test: Presubmit (javadoc only change)

Change-Id: Ifb3f809578be8edd678ea0aacde0254b22db8ffe
2 files changed
tree: f7ab13be3626daa5fa1b69849ff64bfe747620d7
  1. apex/
  2. flags/