Remove a static_assert (#5643)

Having a static_assert on MSAN and ASAN prevents
the fuzzers from being used with different engines,
like TSAN, UBSAN, … but also with fuzzers that aren't
using MSAN/ASAN like afl for example.

tests/fuzzer/test_init.h

@@ -5,10 +5,6 @@
 #include "fuzzer_assert.h"
 #include "test_assert.h"
 
-static_assert(__has_feature(memory_sanitizer) ||
-                  __has_feature(address_sanitizer),
-              "sanitizer disabled");
-
 // Utility for test run.
 struct OneTimeTestInit {
   // Declare trap for the Flatbuffers test engine.