node test: Remove complicated pm_list test.

This test mostly tests logic that I'm about
to remove in subsequent commits, and it's a bit
messy.

This commit removes 100% line coverage, but I
will restore that a few commits later.

tools/test-js-with-node

@@ -59,7 +59,6 @@ enforce_fully_covered = {
     'static/js/narrow_state.js',
     'static/js/people.js',
     'static/js/pm_conversations.js',
-    'static/js/pm_list.js',
     'static/js/presence.js',
     'static/js/reactions.js',
     'static/js/recent_senders.js',