tests: Cleanup test_message_edit_notifications.
tests: Cleanup test_message_edit_notifications.

We add a `_send_and_update_message` function to
de-duplicate it's action.

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