reduce required memory for building image

Author: timfel

mx.graalpython/native-image.properties

@@ -3,7 +3,7 @@
 
 Requires = language:regex language:llvm language:nfi
 
-JavaArgs = -Xmx12G -Dpolyglot.image-build-time.PreinitializeContexts=python
+JavaArgs = -Xmx5100M -Dpolyglot.image-build-time.PreinitializeContexts=python
 
 # TODO --enable-all-security-services is deprecated in 22.0
 Args = -H:MaxRuntimeCompileMethods=20000 \