Hide service users in attention set related components.

1. Do not show service users in the 'Reviewers' dashboard column.
2. Do not show them in the MODIFY attention set section in the reply
   dialog.
3. Never show an attention icon for them in an account label.

Change-Id: I4b38f8832e05edaa49acd683126d1bd7d5c1c5ff
diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js
index 6ccca94..16d6877 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js
@@ -39,6 +39,7 @@
 import {fetchChangeUpdates} from '../../../utils/patch-set-util.js';
 import {KeyboardShortcutMixin} from '../../../mixins/keyboard-shortcut-mixin/keyboard-shortcut-mixin.js';
 import {getDisplayName} from '../../../utils/display-name-util.js';
+import {removeServiceUsers} from '../../../utils/account-util.js';
 
 const STORAGE_DEBOUNCE_INTERVAL_MS = 400;
 
@@ -899,11 +900,15 @@
     if (this._uploader) allAccounts.push(this._uploader);
     if (this._reviewers) allAccounts = [...allAccounts, ...this._reviewers];
     if (this._ccs) allAccounts = [...allAccounts, ...this._ccs];
-    return allAccounts;
+    return removeServiceUsers(allAccounts);
+  }
+
+  _removeServiceUsers(accounts) {
+    return removeServiceUsers(accounts);
   }
 
   _computeShowAttentionCcs(ccs) {
-    return !!ccs && ccs.length > 0;
+    return removeServiceUsers(ccs).length > 0;
   }
 
   _computeUploader(change) {