MM-54181 : Clean up code around deprecated Gfycat (#24343)

* first pass of removal

* first pass of removal

* Update admin_console.js

* rev beta

* remove more

* Update initial_state.ts

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Co-authored-by: Mattermost Build <build@mattermost.com>

webapp/channels/package.json

@@ -40,7 +40,6 @@
     "fast-deep-equal": "3.1.3",
     "flexsearch": "0.6.32",
     "font-awesome": "4.7.0",
-    "gfycat-sdk": "1.4.18",
     "highlight.js": "11.6.0",
     "history": "4.10.1",
     "hoist-non-react-statics": "3.3.2",