Avoid using deprecated exports, fields, and duplicate code (#12555)

src/MatrixClientPeg.ts

@@ -78,15 +78,6 @@ export interface IMatrixClientPeg {
      */
     opts: IStartClientOpts;
 
-    /**
-     * Return the server name of the user's homeserver
-     * Throws an error if unable to deduce the homeserver name
-     * (e.g. if the user is not logged in)
-     *
-     * @returns {string} The homeserver name, if present.
-     */
-    getHomeserverName(): string;
-
     /**
      * Get the current MatrixClient, if any
      */
@@ -384,14 +375,6 @@ class MatrixClientPegClass implements IMatrixClientPeg {
         logger.log(`MatrixClientPeg: MatrixClient started`);
     }
 
-    public getHomeserverName(): string {
-        const matches = /^@[^:]+:(.+)$/.exec(this.safeGet().getSafeUserId());
-        if (matches === null || matches.length < 1) {
-            throw new Error("Failed to derive homeserver name from user ID!");
-        }
-        return matches[1];
-    }
-
     private namesToRoomName(names: string[], count: number): string | undefined {
         const countWithoutMe = count - 1;
         if (!names.length) {