release config is now protobuf

Use `release_config_map.textproto` instead of relying on platform/build
to intuit that for us.

Bug: 328495189
Flag: build.RELEASE_BUILD_FLAGS_IN_PROTOBUF
Test: manual, TH
Ignore-AOSP-First: merge conflict for aosp/3146674
Change-Id: I4573cc04c8bf3116e1a8b728b819b09d6b3a87a3