fix(drill): specify an SA URL parm of impersonation_target for drill+sadrill (#19252)

* Update drill+sadrill to specify an SA URL parm of "impersonation_target".

Sqlalchemy-drill is being updated to support impersonation with the
drill+sadrill driver, where previously it did not.  The way that callers
should specify impersonation matches that for the drill+jdbc driver in that
a SA URL parameter of impersonation_target should be set to the username
of the user to be impersonated, while the stadard SA username and password
should be those of the proxy user.

* Remove lint.

* Address review comments.

* Use idiomatic pytest to test for a raised exception.

* Fix import statement order in drill.py.

superset/db_engine_specs/drill.py

@@ -21,6 +21,7 @@ from urllib import parse
 from sqlalchemy.engine.url import URL
 
 from superset.db_engine_specs.base import BaseEngineSpec
+from superset.db_engine_specs.exceptions import SupersetDBAPIProgrammingError
 from superset.utils import core as utils
 
 
@@ -84,7 +85,9 @@ class DrillEngineSpec(BaseEngineSpec):
         if impersonate_user and username is not None:
             if url.drivername == "drill+odbc":
                 url.query["DelegationUID"] = username
-            elif url.drivername == "drill+jdbc":
+            elif url.drivername in ["drill+sadrill", "drill+jdbc"]:
                 url.query["impersonation_target"] = username
             else:
-                url.username = username
+                raise SupersetDBAPIProgrammingError(
+                    f"impersonation is not supported for {url.drivername}"
+                )