(PE-5885) Ensure puppet-server is stopped before cleaning certs.

This will prevent cert cleaning from happening while puppet-server is still
starting up, for example when one of the last actions by the previous test case
was to restart the master.

Signed-off-by: Wayne <wayne@puppetlabs.com>
(MAINT) Perform more thorouch ssl cleanup.

This only affects puppet-server master behavior. We have found in the past that
failure during these tests can leave the filesystem in an undesirable state for
future tests.

Signed-off-by: Wayne <wayne@puppetlabs.com>
(MAINT) Fix `reset_agent_ssl`.

Don't clear certs on master if master is puppet-server.

Signed-off-by: Wayne <wayne@puppetlabs.com>