Revert "Rename the Graal.js installable."

This reverts commit 6e62abd.

Author: ansalond

graal-js/mx.graal-js/mx_graal_js.py

@@ -339,7 +339,6 @@ def is_included(path):
     suite=_suite,
     name='Graal.js',
     short_name='js',
-    installable_id='javascript',
     standalone_dir_name='graaljs-<version>-<graalvm_os>-<arch>',
     standalone_dependencies={
         'GraalVM license files': ('', ['GRAALVM-README.md']),