node tests: Clean up muting tests.
node tests: Clean up muting tests.

    * move one test below setup
    * add a test() wrapper to clear mutes
    * split up a test
    * use two different dates for java vs. gossip
    * deterministically sort by date

All these changes make it so that the order of
the tests is a lot less fragile.

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