remove redundant background thread for SequelVarz

This creates its own thread that updates
VCAP::Component.varz[:vcap_sequel] every second.

I can find no reference to vcap_sequel in
cloud_controller_ng.

I removed this and all tests pass.
[#56371214] CC stores syslog_drain_url when returned by brokers during bind
Merge branch 'pr/86'
[#56371214] Pass syslog_drain_url down to DEA during app start
backfilled unit test in service provisioner