message send: Refactor how user data is sent for the event.
message send: Refactor how user data is sent for the event.

This is a prep change for calling `get_active_presence_idle_user_ids`
after we have collected all user data variables, so that that function
does not erroneously skip some user IDs from not having the complete
data.

zulip/zulip,andersk/zulip,rht/zulip,andersk/zulip,kou/zulip,eeshangarg/zulip,punchagan/zulip,zulip/zulip,zulip/zulip,kou/zulip,andersk/zulip,andersk/zulip,rht/zulip,zulip/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,kou/zulip,kou/zulip,kou/zulip,kou/zulip,eeshangarg/zulip,zulip/zulip,hackerkid/zulip,eeshangarg/zulip,rht/zulip,hackerkid/zulip,rht/zulip,punchagan/zulip,zulip/zulip,punchagan/zulip,rht/zulip,hackerkid/zulip,andersk/zulip,punchagan/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,punchagan/zulip,andersk/zulip,hackerkid/zulip,hackerkid/zulip