surfaceflinger: put RefreshRateOverlay in the center for circular displays

- Use debug.sf.show_refresh_rate_overlay_in_middle sysprop to turn on.

Test: Visual
Before: screenshot/3nJHsbGsXAjLWNr
After: screenshot/3RtYGnCAe5M2Pf9

Bug: 265356373
Change-Id: Ib598e6f5c7a1c4b13fa4d6e4dbc2e29b2e25bfc8
6 files changed