Dropping support for url_prefix for RealmPlayground, the server now uses
url_template instead only for playground creation, retrieval and audit
logging upon removal.
This does the necessary handling so that url_template is expanded with
the extracted code.
Fixes#25723.
Signed-off-by: Zixuan James Li <p359101898@gmail.com>
initialization function.
We are already importing `generated_pygments_data.json` directly in
`realm_playground.js` so there is no need to pass it via initialization
method.