tests: remove secp256k1_fe_verify from tests.c and modify secp256k1_fe_from_storage to call secp256k1_fe_verify

1. secp256k1_fe_verify is removed from tests since, it throws an error if VERIFY is not defined during compilation.
   (Ex: ./configure --enable-coverage)
2. `secp256k1_fe_from_storage` calls `secp256k1_fe_verify` in the VERIFY build to check for invalid field element.

src/field_5x52_impl.h

@@ -496,6 +496,7 @@ static SECP256K1_INLINE void secp256k1_fe_from_storage(secp256k1_fe *r, const se
 #ifdef VERIFY
     r->magnitude = 1;
     r->normalized = 1;
+    secp256k1_fe_verify(r);
 #endif
 }