Update OWNERS file for B&R

1. Remove people who left the team and add new joiners.
2. Update component id to Platform Core component.
3. Add 'set noparent' make sure owners of the higher-level dirs don't
   automatically become owners of B&R code.

Bug: 254231632
Change-Id: If09e89cf30617ef6db55b4ac9df7f81a69ff5e8b
Test: n/a
1 file changed