test.py: shutdown connection manually
test.py: shutdown connection manually

To prevent async scheduling issues of reconnection after tests are done,
manually close the connection after fixture ends.

Signed-off-by: Alejo Sanchez <004be06a28e38b437b038f9b5c0b9f5758b792e9@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla