Add test to ensure Zen logging enums stay up to date

(Note that there is nothing zen-specific about the guts of the test, so the same structure could be used for similar verifications in other logging protos, if necessary).

Fixes: 324888413
Test: atest ZenEnumTest
Change-Id: I38c85abcba596c78af3c4375adfddd4be3a5fd20