stream_settings: Sort subscriber list by name always.
stream_settings: Sort subscriber list by name always.

This commit changes the behavior of subscriber list to
always be sorted by name instead of sorting them by email
when emails are accessible.

This change is fine because we will be using user-level
email address visibility and in that case the email of
some users will be visible and email of some will be not.

rht/zulip,eeshangarg/zulip,zulip/zulip,zulip/zulip,rht/zulip,eeshangarg/zulip,andersk/zulip,kou/zulip,andersk/zulip,zulip/zulip,eeshangarg/zulip,rht/zulip,kou/zulip,kou/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,zulip/zulip,andersk/zulip,rht/zulip,rht/zulip,andersk/zulip,zulip/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,eeshangarg/zulip,andersk/zulip,kou/zulip,rht/zulip,andersk/zulip,rht/zulip,eeshangarg/zulip,andersk/zulip,kou/zulip