node tests: Prevent zjquery leaks in pm_list.
node tests: Prevent zjquery leaks in pm_list.

We weren't leaking anything, but this change
prevents future leaks.

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