Add -J-XX:MaxRAMPercentage=90.0 on graalpy native / libpythonvm builds

Author: Ariouz

ci.jsonnet

@@ -101,7 +101,7 @@
     local GRAAL_JDK_LATEST          = "graal-jdk-latest",
     local TAGGED_UNITTESTS_SPLIT    = 8,
     local COVERAGE_SPLIT            = 3,
-    local RETAGGER_SPLIT            = 16,
+    local RETAGGER_SPLIT            = 8,
 
     // -----------------------------------------------------------------------------------------------------------------
     // gates

mx.graalpython/mx_graalpython.py

@@ -255,7 +255,7 @@ def libpythonvm_build_args():
     build_args += bytecode_dsl_build_args()
 
     if os.environ.get("GITHUB_CI"):
-        build_args += ["-Ob"]
+        build_args += ["-Ob", "-J-XX:MaxRAMPercentage=90.0"]
 
     if graalos := ("musl" in mx_subst.path_substitutions.substitute("<multitarget_libc_selection>")):
         build_args += ['-H:+GraalOS']