refactor: Inline _check_key_metadata.
refactor: Inline _check_key_metadata.

This was only called in one place.

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