bulk_get_subscriber_user_ids: Use cursor.execute correctly.
bulk_get_subscriber_user_ids: Use cursor.execute correctly.

Signed-off-by: Anders Kaseorg <dfdb7392591db597bc41cf266a9c3bc12a2706e5@zulip.com>

timabbott/zulip,eeshangarg/zulip,kou/zulip,timabbott/zulip,brainwane/zulip,andersk/zulip,rht/zulip,zulip/zulip,hackerkid/zulip,hackerkid/zulip,brainwane/zulip,eeshangarg/zulip,timabbott/zulip,hackerkid/zulip,kou/zulip,kou/zulip,showell/zulip,showell/zulip,synicalsyntax/zulip,eeshangarg/zulip,rht/zulip,rht/zulip,shubhamdhama/zulip,andersk/zulip,kou/zulip,eeshangarg/zulip,kou/zulip,showell/zulip,zulip/zulip,shubhamdhama/zulip,zulip/zulip,andersk/zulip,eeshangarg/zulip,synicalsyntax/zulip,punchagan/zulip,hackerkid/zulip,kou/zulip,shubhamdhama/zulip,timabbott/zulip,kou/zulip,showell/zulip,zulip/zulip,rht/zulip,brainwane/zulip,brainwane/zulip,brainwane/zulip,synicalsyntax/zulip,showell/zulip,eeshangarg/zulip,hackerkid/zulip,timabbott/zulip,timabbott/zulip,punchagan/zulip,zulip/zulip,rht/zulip,timabbott/zulip,brainwane/zulip,shubhamdhama/zulip,shubhamdhama/zulip,andersk/zulip,punchagan/zulip,rht/zulip,punchagan/zulip,zulip/zulip,punchagan/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,andersk/zulip,showell/zulip,rht/zulip,brainwane/zulip,andersk/zulip,punchagan/zulip,synicalsyntax/zulip,eeshangarg/zulip,synicalsyntax/zulip,hackerkid/zulip,synicalsyntax/zulip,shubhamdhama/zulip,zulip/zulip,shubhamdhama/zulip,synicalsyntax/zulip,showell/zulip