tests: zero-init ccmTag to satisfy clang-tidy

clang-tidy (all-c89, async-quic, intelasm) flagged `ccmTag[0] ^= 0x01` as a use
of an uninitialized value: the analyzer does not model wc_AesCcmEncrypt writing
the tag buffer. Zero-initialize ccmTag; the subsequent encrypt still overwrites
it before the tamper, so behavior is unchanged.

tests/api/test_aes.c

@@ -8514,7 +8514,7 @@ int test_wc_AesFeatureCoverage(void)
         };
         Aes aes;
         byte ccmCipher[sizeof(ccmPlain)];
-        byte ccmTag[16];
+        byte ccmTag[16] = { 0 };
         byte ccmRecovered[sizeof(ccmPlain)];
         int initDone = 0;