Refactor/migrate/autocomplete database speabase specs to ts (#27837)

* refactor: migrate database/users_spec.js to ts

- migrate file autocomplete/database/users_spec.js to typescripts
- udpate system.d.ts data type adding type
for shouldHaveElasticsearchDisabled

* refactor: migrate users_in_channel_switcher_spec.js

- migrate file users_in_channel_switcher_spec to typescript
- fix issue with data type on file autocomplete/helpers.ts
function verifySuggestionAtChannelSwitcher
- fix issue with data type on file autocomplete/common_test.ts
function doTestQuickChannelSwitcher

* refactor: migrate users_in_message_input_box_spec to ts

- migrate file database/users_in_message_input_box_spec.js to typescript
- migrate file support/ui/suggestion_list.js to typescript and update
docs and type definitions
- update references to doTestPostextbox function
- update references to verifySuggestionAtPostTextbox function

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

e2e-tests/cypress/tests/support/api/system.d.ts

@@ -146,6 +146,14 @@ declare namespace Cypress {
          */
         apiInvalidateCache(): Chainable<Record<string, any>>;
 
+        /**
+         * Allow test if matches elastic search disabled.
+         * Otherwise, fail fast.
+         * @example
+         *   cy.shouldHaveElasticsearchDisabled();
+         */
+        shouldHaveElasticsearchDisabled(): Chainable;
+
         /**
          * Allow test for server other than Cloud edition or with Cloud license.
          * Otherwise, fail fast.