Set installable_id to 'python'

Author: fangerer

mx.graalpython/mx_graalpython.py

@@ -1406,7 +1406,7 @@ def verify_ci(dest_suite, common_ci_dir="ci_common", args=None, ext=('.jsonnet',
     suite=SUITE,
     name='Graal.Python',
     short_name='pyn',
-    installable_id='graalpython',
+    installable_id='python',
     dir_name='python',
     standalone_dir_name='graalpython-<version>-<graalvm_os>-<arch>',
     license_files=[],