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

---------

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

e2e-tests/playwright/support/server/default_config.ts

@@ -127,8 +127,6 @@ const defaultServerConfig: AdminConfig = {
         WebsocketPort: 80,
         WebserverMode: 'gzip',
         EnableGifPicker: true,
-        GfycatAPIKey: '2_KtH_W5',
-        GfycatAPISecret: '3wLVZPiswc3DnaiaFoLkDvB4X0IV6CpMkj4tf2inJRsBY6-FnkT08zGmppWFgeof',
         GiphySdkKey: 's0glxvzVg9azvPipKxcPLpXV0q1x1fVP',
         EnableCustomEmoji: true,
         EnableEmojiPicker: true,