About: fix binding loop

"anchors.centerIn: parent" caused a binding loop
with parent implicitHeight using contentHeight in Control.qml
Removing "anchors.centerIn: parent" fixed the warning while the
popup remains in the center of the page

Gitlab: #1508

Change-Id: I0d05597100e4c2b306180e83a7b88b6d5ee22f40

src/app/commoncomponents/BaseModalDialog.qml

@@ -57,7 +57,6 @@ Popup {
         id: container
 
         property color color: JamiTheme.secondaryBackgroundColor
-        anchors.centerIn: parent
         leftPadding: popupMargins
         bottomPadding: action1.visible || action2.visible ? 10 :popupMargins