AOSP/Messaging - Remove TEST_MAPPING because presubmit tests fail on build_target: aosp_cf_x86_phone-userdebug

BUG: 126516784

Test: No impact. TEST_MAPPING wasn't enabled before, thus removing the file shouldn't have an impact.
Change-Id: Ib206cb6d921b59a032e6557352c6961310b08272
1 file changed