Added Cypress tests and few optimizations (#24592)

* added e2e test

* Cleanup

* Unused permission

* Minor changes

* Added case when there is no common team

* More tests

* nit

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

@@ -212,5 +212,14 @@ declare namespace Cypress {
          *   });
          */
         apiCreateArchivedChannel(name: string, displayName: string, type: string, teamId: string, messages?: string[], user?: UserProfile): Chainable<Channel>;
+
+        /**
+         * Command to convert a GM to a private channel
+         * @param {string} channelId - channel id of GM to be converted
+         * @param {string} teamId - id of team to move the converted private channel to
+         * @param {string} displayName - display name of converted channel
+         * @param {string} name - name of converted channel
+         */
+        apiConvertGMToPrivateChannel(channelId: string, teamId: string, displayName: string, name: string): Chainable;
     }
 }

e2e-tests/cypress/tests/support/api/channel.js

@@ -186,3 +186,19 @@ Cypress.Commands.add('apiCreateArchivedChannel', (name, displayName, type = 'O',
         return cy.wrap(channel);
     });
 });
+
+Cypress.Commands.add('apiConvertGMToPrivateChannel', (channelId, teamId, displayName, name) => {
+    const body = {
+        channel_id: channelId,
+        team_id: teamId,
+        display_name: displayName,
+        name,
+    };
+
+    return cy.request({
+        headers: {'X-Requested-With': 'XMLHttpRequest'},
+        url: `/api/v4/channels/${channelId}/convert_to_channel?team_id=${teamId}`,
+        method: 'POST',
+        body,
+    });
+});