Remove in-product pricing modal (#31187)

* Remove pricing modal. Adjust everywhere to instead open mattermost.com/pricing. When air gapped, don't show buttons to view plans.

* Fix lint

* Further clean up of unused code. Fixes for linter

* fixes for PR feedback

* useExternalLink for opening pricing modal with enriched params

* Fix i17n

* Fix style, tests

webapp/platform/client/src/client4.ts

@@ -4004,12 +4004,6 @@ export default class Client4 {
         );
     };
 
-    getSelfHostedProducts = () => {
-        return this.doFetch<Product[]>(
-            `${this.getCloudRoute()}/products/selfhosted`, {method: 'get'},
-        );
-    };
-
     subscribeToNewsletter = (newletterRequestBody: NewsletterRequestBody) => {
         return this.doFetch<StatusOK>(
             `${this.getHostedCustomerRoute()}/subscribe-newsletter`,