Drop exec from description

`exec` is not a real thing. There's `executable`, there's `exe`, but neither add value here.

src/main/resources/com/google/jenkins/plugins/computeengine/InstanceConfiguration/config.jelly

@@ -50,7 +50,7 @@
             <f:entry title="${%Remote Location}" field="remoteFs">
                 <f:textbox default=""/>
             </f:entry>
-            <f:entry title="${%Java Exec Path}" field="javaExecPath">
+            <f:entry title="${%Java Path}" field="javaExecPath">
                 <f:textbox default="java"/>
             </f:entry>
             <f:optionalProperty field="windowsConfiguration" title="${%Windows?}">