server_events_dispatch: Refactor subscription case to use switch/case.
server_events_dispatch: Refactor subscription case to use switch/case.

This commit should make no behavioural changes.

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