Fix asan/tsan env options handling (#55753)

Summary:
Pull Request resolved: #55753

The warning "ASAN and TSAN modes cannot be used together" was incorrectly displayed when only ASAN was enabled. This happened because the condition checked only `enableASAN` instead of `enableASAN && enableTSAN`. Updated the conditional logic to properly check that both flags are enabled before showing the conflict warning.

Changelog: [Internal]

Reviewed By: NickGerleman

Differential Revision: D94393117

fbshipit-source-id: f7a96de11230710e8d54c17d4c89edb569ebaa07

Author: Nick Lefever

private/react-native-fantom/runner/utils.js

@@ -70,7 +70,7 @@ export function getBuckModesForPlatform(
       });
     }
   } else {
-    if (EnvironmentOptions.enableASAN) {
+    if (EnvironmentOptions.enableASAN && EnvironmentOptions.enableTSAN) {
       printConsoleLog({
         type: 'console-log',
         level: 'warn',