queue processors: Switch SignupWorker to logging user IDs.
queue processors: Switch SignupWorker to logging user IDs.

This is a better setup than logging emails, especially with
EMAIL_ADDRESS_VISIBILITY_ADMINS.

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