[SB][Screen Chips] Convert MediaProjectionRepo logs to LogBuffer.

Bug: 351785188
Bug: 332662551

Flag: com.android.systemui.status_bar_screen_sharing_chips
Flag: com.android.systemui.pss_task_switcher

(Note on flag stanzas: This repository is used by two features, each
guarded by one of those flags)

Test: Projection screen to different apps, then dump `MediaProjection`
-> verify logging
Test: atest MediaProjectionManagerRepositoryTest

Change-Id: I76776abdd60ee4cddcd0bec636c445c99982ed13