Fix warnings in .ui (linux)

Fix various warnings emitted by uic

Author: howetuft

src/MEGASync/gui/linux/AddExclusionDialog.ui

@@ -158,7 +158,6 @@ font-size: 11px;
        </widget>
       </item>
      </layout>
-     <zorder>horizontalSpacer</zorder>
      <zorder>bCancel</zorder>
      <zorder>bOk</zorder>
      <zorder>bChoose</zorder>

src/MEGASync/gui/linux/ChangePassword.ui

@@ -200,7 +200,6 @@
        </widget>
       </item>
      </layout>
-     <zorder>horizontalSpacer</zorder>
      <zorder>bCancel</zorder>
      <zorder>bOk</zorder>
     </widget>

src/MEGASync/gui/linux/SettingsDialog.ui

@@ -3104,7 +3104,7 @@ padding-bottom: 3px;</string>
               <verstretch>0</verstretch>
              </sizepolicy>
             </property>
-            <layout class="QHBoxLayout" name="horizontalLayout_20">
+            <layout class="QHBoxLayout" name="horizontalLayout_201">
              <property name="leftMargin">
               <number>0</number>
              </property>