remove redis-mock (#23051)

Part of #1265

Author: Peter Bengtsson

package-lock.json

@@ -73,7 +73,6 @@
     "react-markdown": "^7.1.0",
     "react-syntax-highlighter": "^15.4.4",
     "redis": "^3.1.2",
-    "redis-mock": "^0.56.3",
     "rehype-autolink-headings": "^6.1.0",
     "rehype-highlight": "^5.0.0",
     "rehype-raw": "^6.1.0",