This ensures that all APIs that generate new keys from KeyTemplate can
generate keys with non-TINK prefix types.

If a key template proto does not contain an output prefix type, uses
the TINK prefix type.

Change-Id: I041c335eabaa87c41c88bbe5e51ee02c867b6970
ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>
GitOrigin-RevId: 87d37eb7bba823db0b5f00f70ca247ffcc1d1ade