revert gradle memory change

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1898323 13f79535-47bb-0310-9956-ffa450edef68

gradle.properties

@@ -1,7 +1,7 @@
 # Specifies the JVM arguments used for the daemon process.
 # The setting is particularly useful for tweaking memory settings.
 # Less than 2G definitely slows things down. -XX:+HeapDumpOnOutOfMemoryError
-org.gradle.jvmargs=-Xmx4G -Dfile.encoding=UTF-8
+org.gradle.jvmargs=-Xmx2G -Dfile.encoding=UTF-8
 
 # Activating will be much faster, but break the build of 'poi-ooxml-lite'
 # @todo: look into poi-ooxml-lite task generateModuleInfo and enforce running whatever is needed before