[Clipboard] Use ellipsis in the search field label ('Search...' instead of 'Search')

Summary: This patch adds the ellipsis (...) to the search field label in Clipboard so as to make it consistent with the labels in Kickoff, Kicker and KRunner.

Test Plan:
Before:
{F6521497}
After:
{F6521498}

Reviewers: ngraham, #plasma, #vdg

Reviewed By: ngraham, #vdg

Subscribers: abetts, filipf, plasma-devel

Tags: #plasma

Maniphest Tasks: T10258

Differential Revision: https://phabricator.kde.org/D17935

applets/clipboard/contents/ui/ClipboardPage.qml

@@ -91,7 +91,7 @@ ColumnLayout {
 
         PlasmaComponents.TextField {
             id: filter
-            placeholderText: i18n("Search")
+            placeholderText: i18n("Search...")
             clearButtonShown: true
             Layout.fillWidth: true
         }