Pin react-native-onyx to visibilitychange probe commit

Pins onyx to callstack-internal/react-native-onyx@7ac9c50a (Expensify/react-native-onyx#798)
so E/App CI runs the full suite against the proactive IDB visibilitychange probe change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: elirangoshen

package-lock.json

@@ -192,7 +192,7 @@
     "react-native-localize": "^3.5.4",
     "react-native-nitro-modules": "0.35.0",
     "react-native-nitro-sqlite": "9.6.0",
-    "react-native-onyx": "3.0.79",
+    "react-native-onyx": "git+https://github.com/callstack-internal/react-native-onyx.git#7ac9c50ac0b853e09bf7ffe8e5299ea410edf069",
     "react-native-pager-view": "8.0.0",
     "react-native-pdf": "7.0.2",
     "react-native-permissions": "^5.4.0",