Standardize margin on digitizing page

Author: nyalldawson

src/ui/qgsvectorlayerpropertiesbase.ui

@@ -2345,6 +2345,18 @@ border-radius: 2px;</string>
          </widget>
          <widget class="QWidget" name="mOptsPage_Digitizing">
           <layout class="QGridLayout" name="gridLayout_12">
+           <property name="leftMargin">
+            <number>0</number>
+           </property>
+           <property name="topMargin">
+            <number>0</number>
+           </property>
+           <property name="rightMargin">
+            <number>0</number>
+           </property>
+           <property name="bottomMargin">
+            <number>0</number>
+           </property>
            <item row="0" column="0">
             <widget class="QGroupBox" name="groupBox">
              <property name="title">