Remove an unnecessary check before running db_stress (#6231)

Summary:
As title. We can run non-cf-consistency stress tests with verify_db_one_in>0,
thus remove the check added previously.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6231

Test Plan:
```
make crash_test
```

Differential Revision: D19198295

Pulled By: riversand963

fbshipit-source-id: e874c701bb03ab76eaab00f059dd4032bb2f537f

db_stress_tool/db_stress_tool.cc

@@ -192,13 +192,6 @@ int db_stress_tool(int argc, char** argv) {
     exit(1);
   }
 
-  if (!FLAGS_test_cf_consistency && FLAGS_verify_db_one_in > 0) {
-    fprintf(stderr,
-            "For non cf_consistency tests, VerifyDb() is called only before "
-            "and after test.\n");
-    exit(1);
-  }
-
   rocksdb_kill_odds = FLAGS_kill_random_test;
   rocksdb_kill_prefix_blacklist = SplitString(FLAGS_kill_prefix_blacklist);