Fix launcher unit tests not passing because of containers

Before submitting the issue

[X] I have searched among the existing issues
[X] I am using a Python virtual environment

Description of the bug

If #1238 gets approved, the launcher module will be almost fully operative.

But there will be some tests not passing.

Test not passing.


==================================================== short test summary info =====================================================
FAILED tests/test_launcher.py::test_invalid_mode - IndexError: list index out of range
FAILED tests/test_launcher.py::test_license_type_keyword - Failed: DID NOT WARN. No warnings of type (<class 'UserWarning'>,) w...
FAILED tests/test_launcher.py::test_license_type_keyword_names - AssertionError: assert 'Ansys Mechanical Enterprise Solver' in...
FAILED tests/test_launcher.py::test_license_type_additional_switch - Failed: DID NOT WARN. No warnings of type (<class 'UserWar...
==================================== 4 failed, 19 passed, 5 skipped, 1094 deselected in 7.11s ====================================

They need further investigation (probably access to the license server?)

Also the can_start_instance needs to be removed. It has been put there because get_start_instance needs to be re-worked.

Steps To Reproduce

N/A

Which Operating System are you using?

Linux

Which Python version are you using?

3.8

Installed packages

N/A

ansys / pymapdl

Fix launcher unit tests not passing because of containers #1250