jira: Do not assign sub-tasks on release start

Do not assign sub-tasks to JIRA versions. It is not really necessary
since the parent issues represents what needs to be done and the
sub-tasks would only polute the version overview.

Change-Id: 4aadb43410
Story-Id: SF-77
wip [ci skip]

Change-Id: 34a4bd1fcb
wip [ci skip]

Change-Id: 4a5feeeec5
wip [ci skip]

Change-Id: 1b2e81f9fc
wip [ci skip]

Change-Id: 706d3a0ee5
wip [ci skip]

Change-Id: ba61468aee
wip [ci skip]

Change-Id: 8ccba5e64a
wip [ci skip]

Change-Id: 242f0c19f5
wip [ci skip]

Change-Id: d4109e3f1d
wip [ci skip]

Change-Id: b89083862f