ui_session: return airgun session as a context manager (#15050)

In `Satellite.ui_session()` context manager method,
`airgun.session.Session()` is also a context manager
and needs to be returned using the `with-yield` contruct,
so the Session's `__enter__` and `__exit__` methods are executed.

This fixes the problem where `Session.__exit__()` method was not called
and thus screenshot was not taken and the browser window was not closed
at the end of the test.

Also the `except Exception: raise` part was removed as redundant.

(cherry picked from commit 2618e01)

robottelo/hosts.py

@@ -1766,17 +1766,15 @@ def get_caller():
             return None
 
         try:
-            ui_session = Session(
+            with Session(
                 session_name=testname or get_caller(),
                 user=user or settings.server.admin_username,
                 password=password or settings.server.admin_password,
                 url=url,
                 hostname=self.hostname,
                 login=login,
-            )
-            yield ui_session
-        except Exception:
-            raise
+            ) as ui_session:
+                yield ui_session
         finally:
             video_url = settings.ui.grid_url.replace(
                 ':4444', f'/videos/{ui_session.ui_session_id}.mp4'