MM-52173 Add setting to delay channel autocomplete (#22952)

* Add unit tests for ChannelMentionProvider.handleCompleteWord

* Add a minimum length before the ChannelMentionProvider triggers

* MM-52173 Move delayed autcomplete behind a setting

* Fix e2e test type check

* Update Textbox tests

* Add new setting to server telemetry

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

@@ -532,6 +532,7 @@ const defaultServerConfig: AdminConfig = {
         EnableAppBar: false,
         PatchPluginsReactDOM: false,
         DisableRefetchingOnBrowserFocus: false,
+        DelayChannelAutocomplete: false,
     },
     AnalyticsSettings: {
         MaxUsersForStatistics: 2500,