Make `our_realm` explicit in `bulk_remove_subscriptions`.
Make `our_realm` explicit in `bulk_remove_subscriptions`.

There's an implicit assumption in bulk_remove_subscriptions
that all users belong to the same realm.  We use the realm
for things like comparing occupied streams before and
after our main operation of deactivating streams.

Before this change, we just used the user_profile variable
that leaked from some prior loop to look up the realm, which
was super brittle.

Now we're a bit more explicit.

showell/zulip,timabbott/zulip,hackerkid/zulip,brockwhittaker/zulip,tommyip/zulip,rishig/zulip,synicalsyntax/zulip,synicalsyntax/zulip,timabbott/zulip,brockwhittaker/zulip,rht/zulip,dhcrzf/zulip,hackerkid/zulip,dhcrzf/zulip,mahim97/zulip,rht/zulip,zulip/zulip,brainwane/zulip,kou/zulip,zulip/zulip,andersk/zulip,zulip/zulip,zulip/zulip,brainwane/zulip,shubhamdhama/zulip,dhcrzf/zulip,punchagan/zulip,brainwane/zulip,mahim97/zulip,eeshangarg/zulip,eeshangarg/zulip,hackerkid/zulip,mahim97/zulip,kou/zulip,hackerkid/zulip,tommyip/zulip,punchagan/zulip,kou/zulip,shubhamdhama/zulip,jackrzhang/zulip,Galexrt/zulip,eeshangarg/zulip,rht/zulip,zulip/zulip,eeshangarg/zulip,punchagan/zulip,brockwhittaker/zulip,jackrzhang/zulip,punchagan/zulip,mahim97/zulip,hackerkid/zulip,andersk/zulip,jackrzhang/zulip,brockwhittaker/zulip,kou/zulip,punchagan/zulip,shubhamdhama/zulip,punchagan/zulip,timabbott/zulip,tommyip/zulip,brainwane/zulip,Galexrt/zulip,tommyip/zulip,synicalsyntax/zulip,andersk/zulip,shubhamdhama/zulip,tommyip/zulip,Galexrt/zulip,dhcrzf/zulip,showell/zulip,rishig/zulip,kou/zulip,timabbott/zulip,jackrzhang/zulip,rishig/zulip,synicalsyntax/zulip,rishig/zulip,brockwhittaker/zulip,zulip/zulip,synicalsyntax/zulip,eeshangarg/zulip,rishig/zulip,shubhamdhama/zulip,dhcrzf/zulip,timabbott/zulip,brainwane/zulip,rht/zulip,rht/zulip,andersk/zulip,brainwane/zulip,andersk/zulip,dhcrzf/zulip,mahim97/zulip,andersk/zulip,shubhamdhama/zulip,showell/zulip,rishig/zulip,rishig/zulip,mahim97/zulip,showell/zulip,shubhamdhama/zulip,showell/zulip,tommyip/zulip,timabbott/zulip,showell/zulip,tommyip/zulip,synicalsyntax/zulip,dhcrzf/zulip,hackerkid/zulip,eeshangarg/zulip,hackerkid/zulip,Galexrt/zulip,jackrzhang/zulip,rht/zulip,andersk/zulip,zulip/zulip,showell/zulip,brainwane/zulip,eeshangarg/zulip,synicalsyntax/zulip,brockwhittaker/zulip,Galexrt/zulip,jackrzhang/zulip,timabbott/zulip,Galexrt/zulip,kou/zulip,rht/zulip,jackrzhang/zulip,kou/zulip,punchagan/zulip,Galexrt/zulip