settings: Fix last_active sorting in user settings.
settings: Fix last_active sorting in user settings.

We were incorrectly accessing .id, not .user_id, on the people objects.

Fixes #15165.
andersk/zulip,shubhamdhama/zulip,eeshangarg/zulip,punchagan/zulip,punchagan/zulip,rht/zulip,showell/zulip,eeshangarg/zulip,showell/zulip,hackerkid/zulip,showell/zulip,timabbott/zulip,andersk/zulip,timabbott/zulip,synicalsyntax/zulip,shubhamdhama/zulip,eeshangarg/zulip,showell/zulip,timabbott/zulip,punchagan/zulip,andersk/zulip,timabbott/zulip,eeshangarg/zulip,rht/zulip,hackerkid/zulip,shubhamdhama/zulip,andersk/zulip,rht/zulip,zulip/zulip,synicalsyntax/zulip,hackerkid/zulip,timabbott/zulip,andersk/zulip,kou/zulip,punchagan/zulip,kou/zulip,kou/zulip,synicalsyntax/zulip,eeshangarg/zulip,brainwane/zulip,zulip/zulip,kou/zulip,shubhamdhama/zulip,hackerkid/zulip,brainwane/zulip,shubhamdhama/zulip,punchagan/zulip,rht/zulip,showell/zulip,brainwane/zulip,hackerkid/zulip,brainwane/zulip,zulip/zulip,eeshangarg/zulip,brainwane/zulip,shubhamdhama/zulip,brainwane/zulip,kou/zulip,synicalsyntax/zulip,zulip/zulip,kou/zulip,shubhamdhama/zulip,zulip/zulip,punchagan/zulip,andersk/zulip,zulip/zulip,synicalsyntax/zulip,kou/zulip,timabbott/zulip,hackerkid/zulip,rht/zulip,showell/zulip,andersk/zulip,showell/zulip,eeshangarg/zulip,hackerkid/zulip,rht/zulip,synicalsyntax/zulip,brainwane/zulip,synicalsyntax/zulip,zulip/zulip,timabbott/zulip,punchagan/zulip,rht/zulip