Migrate remaining gr-autocomplete usages from error dialog to dropdown.

Rest API failures currently show a dialog. With this change they will
show as dropdown introduced in https://gerrit-review.googlesource.com/c/gerrit/+/353121

After this change the only usages left will be in plugins.

Google-Bug-Id: b/257213270
Release-Notes: skip
Change-Id: Ie291529b38513ce6e9ca20abb95b860f2d1908a0
diff --git a/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts b/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts
index 15ec512..2996e50 100644
--- a/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts
+++ b/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts
@@ -21,6 +21,7 @@
 import {when} from 'lit/directives/when.js';
 import {fire} from '../../../utils/event-util';
 import {PropertiesOfType} from '../../../utils/type-util';
+import {throwingErrorCallback} from '../../shared/gr-rest-api-interface/gr-rest-apis/gr-rest-api-helper';
 
 type NotificationKey = PropertiesOfType<Required<ProjectWatchInfo>, boolean>;
 
@@ -193,13 +194,15 @@
 
   // private but used in tests.
   getProjectSuggestions(input: string) {
-    return this.restApiService.getSuggestedRepos(input).then(response => {
-      const repos: AutocompleteSuggestion[] = [];
-      for (const [name, repo] of Object.entries(response ?? {})) {
-        repos.push({name, value: repo.id});
-      }
-      return repos;
-    });
+    return this.restApiService
+      .getSuggestedRepos(input, /* n=*/ undefined, throwingErrorCallback)
+      .then(response => {
+        const repos: AutocompleteSuggestion[] = [];
+        for (const [name, repo] of Object.entries(response ?? {})) {
+          repos.push({name, value: repo.id});
+        }
+        return repos;
+      });
   }
 
   private handleRemoveProject(project: ProjectWatchInfo) {