flags: Add do_not_replace_existing_cod_with_uncategorized_cod

Introduce a flag that to fix a bug where we replace a known class of
device with one that is uncategorized.

Bug: 335909751
Bug: 315241296
Test: m com.android.btservices
Change-Id: I70be6d0a55159d53754f5e2a20fd36f47dfa8750