refactor(openflare): remove unused About page and API

Delete AboutService and GET /api/v1/d/about since the about page was
never implemented in the Wavelet frontend.

Wavelet/frontend/lib/services/openflare/about.service.ts

@@ -1,7 +0,0 @@
-import {OpenFlareBaseService} from './base.service';
-
-export class AboutService extends OpenFlareBaseService {
-  static getAboutContent(): Promise<string> {
-    return this.get<string>('/about');
-  }
-}

Wavelet/frontend/lib/services/openflare/index.ts

@@ -1,4 +1,3 @@
-export { AboutService } from './about.service';
 export { OpenFlareBaseService } from './base.service';
 
 export { NodeService } from './node.service';
@@ -119,7 +118,6 @@ export type {
   TlsCertificateMutationPayload,
 } from './types';
 
-import {AboutService} from './about.service';
 import {AccessLogService} from './access-log.service';
 import {ApplyLogService} from './apply-log.service';
 import {ConfigVersionService} from './config-version.service';
@@ -138,7 +136,6 @@ import {WafService} from './waf.service';
 import {WebsiteService} from './website.service';
 
 export const openflareServices = {
-  about: AboutService,
   node: NodeService,
   proxyRoute: ProxyRouteService,
   configVersion: ConfigVersionService,