[Calendar] Adjust the calendar toolbar anchors

Summary:
Horizontally align the toolbar row to the days/month/etc grid canvas.

(The bar was used to be a few pixels wider)

Test Plan:
Before: {F5514329}

After: {F5514330}

Reviewers: #plasma, broulik

Reviewed By: #plasma, broulik

Subscribers: aacid, davidedmundson, broulik, plasma-devel, #plasma, #frameworks

Tags: #frameworks, #plasma

Maniphest Tasks: T7499

Differential Revision: https://phabricator.kde.org/D9019

src/declarativeimports/calendar/qml/DaysCalendar.qml

@@ -90,8 +90,8 @@ Item {
     RowLayout {
         anchors {
             top: parent.top
-            left: parent.left
-            right: parent.right
+            left: canvas.left
+            right: canvas.right
         }
         spacing: units.smallSpacing