[test] Fix filecheck annotation typos (llvm#91854)

Similar to rust-lang/rust#125007

Author: klensy

polly/test/CodeGen/alias_metadata_too_many_arrays.ll

@@ -16,7 +16,7 @@
 ;      }
 ;    }
 ;
-; CHECK-LABEL @manyarrays
+; CHECK-LABEL: @manyarrays
 ; CHECK: load{{.*}}!alias.scope
 ; CHECK: store{{.*}}!alias.scope
 ; CHECK: load{{.*}}!alias.scope