Remove one sub test case from dovetail.tempest.tc004

Remove one sub test case from dovetail.tempest.tc004

1. Currently, dovetail.tempest.tc004 has 13 sub test cases defined in its
   config file and specification document of the test case. All these
   sub test cases are picked from tempest based on it's version 15.0.0.
2. For Dovetail 1st release, it fixes the version of Functest to be
   opnfv/dovetail:cvp.0.5.0, and Functest integretes tempest 14.0.0
   in this version and it's E release.
3. There is one sub test case in dovetail.tempest.tc004 that is new in
   tempest 15.0.0, so it can not be recognized and executed by Functest D
   and E release. It is 'test_server_connectivity_cold_migration_revert'.
4. Remove this sub test case from dovetail.tempest.tc004. This means remove it
   from the test case config file and specification document.

JIRA: DOVETAIL-561

Change-Id: Ia927af040794c7027a741a282ed75fe401f99ff1
Signed-off-by: xudan <xudan16@huawei.com>