Handle WEBDRIVER_BASEURL slashes

As suggested, we handle both cases (trailing slash, no trailing slash) for the WEBDRIVER_BASEURL. We use the existing `superset.utils.urls` `get_url_path(...)` function to manage everything.

superset/tasks/cache.py

@@ -31,19 +31,19 @@
 from superset.tags.models import Tag, TaggedObject
 from superset.utils.date_parser import parse_human_datetime
 from superset.utils.machine_auth import MachineAuthProvider
+from superset.utils.urls import get_url_path
 
 logger = get_task_logger(__name__)
 logger.setLevel(logging.INFO)
 
 
 def get_url(chart: Slice, dashboard: Optional[Dashboard] = None) -> str:
     """Return external URL for warming up a given chart/table cache."""
-    with app.test_request_context():
-        baseurl = "{WEBDRIVER_BASEURL}".format(**app.config)
-        url = f"{baseurl}superset/warm_up_cache/?slice_id={chart.id}"
-        if dashboard:
-            url += f"&dashboard_id={dashboard.id}"
-        return url
+    return get_url_path(
+        "Superset.warm_up_cache",
+        slice_id=chart.id,
+        dashboard_id=dashboard.id if dashboard else None,
+    )
 
 
 class Strategy:  # pylint: disable=too-few-public-methods