ProjectExplorer: Raise maximum of parallel jobs

Now to 999 instead of the default of 99.

Change-Id: I58adea913a846d8b775bcacaa7973bde18488ef3
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

src/plugins/projectexplorer/makestep.ui

@@ -79,6 +79,9 @@
        <property name="minimum">
         <number>1</number>
        </property>
+       <property name="maximum">
+        <number>999</number>
+       </property>
       </widget>
      </item>
      <item>