node tests: Fix zjquery leaks in recent_topics.
node tests: Fix zjquery leaks in recent_topics.

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