doc: Remove readonly tag from PinchHandler persistent properties

Amends a432970b25

As a drive-by, remove redundant categorized logging output, which
wrongly implied that starting scale could be set from the target scale.

Pick-to: 6.5 6.6
Task-number: QTBUG-76739
Task-number: QTBUG-94168
Change-Id: I1fad79b58fa20e165fd21bc593a27cff8378b7ea
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

src/quick/handlers/qquickpinchhandler.cpp

@@ -146,7 +146,6 @@ void QQuickPinchHandler::setActiveScale(qreal scale)
 */
 
 /*!
-    \readonly
     \qmlproperty real QtQuick::PinchHandler::persistentScale
 
     The scale factor that will automatically be set on the \l target if it is not null.
@@ -248,7 +247,6 @@ void QQuickPinchHandler::setActiveRotation(qreal rot)
 }
 
 /*!
-    \readonly
     \qmlproperty real QtQuick::PinchHandler::persistentRotation
 
     The rotation to be applied to the \l target if it is not null.
@@ -488,7 +486,7 @@ void QQuickPinchHandler::onActiveChanged()
         m_startDistance = averageTouchPointDistance(centroid().sceneGrabPosition());
         m_startTargetPos = target() ? target()->position() : QPointF();
         qCDebug(lcPinchHandler) << "activated with starting scale" << m_scaleAxis.m_startValue
-                                << "target scale" << m_scaleAxis.m_startValue << "rotation" << m_rotationAxis.m_startValue
+                                << "rotation" << m_rotationAxis.m_startValue
                                 << "target pos" << m_startTargetPos;
     } else {
         m_startTargetPos = QPointF();