feat(vm): added disable connection

[qqmok]

@dweinholz

API: https://github.com/deNBI/simplevm-draft-repo/pull/783
Webapp: https://github.com/deNBI/simplevm-webapp-draft/pull/1135

Try to fulfill the following points before the Pull Request is merged:

• The PR is reviewed by one of the team members.
• If a linting PR exists, it must be merged before this PR is allowed to be merged.
• If the PR is merged in the master then a release should be be made.
• If the new code is readable, if not it should be well commented

For releases only:

• If the review of this PR is approved and the PR is followed by a release then the .env file
  in the cloud-portal repo should also be updated.
• If you are making a release then please sum up the changes since the last release on the release page using the clog tool with clog -F

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
simple_vm_client
VirtualMachineHandler.py	202	114	114	44%
__init__.py	1	0	100%
test_virtualmachinehandler.py	306	195	195	36%
simple_vm_client/benchmark
__init__.py	0	0	100%
test_service.py	52	36	36	31%
simple_vm_client/bibigrid_connector
__init__.py	0	0	100%
bibigrid_connector.py	118	104	104	12%
test_bibigrid_connector.py	173	113	113	35%
simple_vm_client/forc_connector
__init__.py	0	0	100%
forc_connector.py	290	247	247	15%
simple_vm_client/forc_connector/playbook
__init__.py	0	0	100%
playbook.py	190	159	159	16%
test_playbook.py	381	282	282	26%
simple_vm_client/forc_connector/template
__init__.py	0	0	100%
template.py	227	148	148	35%
simple_vm_client/metadata_connector
metadata_connector.py	88	71	71	19%
simple_vm_client/openstack_connector
__init__.py	0	0	100%
openstack_connector.py	969	851	851	12%
simple_vm_client/util
__init__.py	0	0	100%
state_enums.py	70	0	100%
test_thrift_converter.py	170	143	143	16%
thrift_converter.py	80	61	61	24%
TOTAL	3317	2524	24%

Tests	Skipped	Failures	Errors	Time
1	0 💤	0 ❌	1 🔥	2.261s ⏱️