Tests: add support for deadline for automatic tests

[kalisp]

Brief description

First sentence is brief description.

Description

Next paragraf is more elaborate text with more info. This will be displayed for example in collapsed form under the first sentence in a changelog.

Additional info

The rest will be ignored in changelog and should contain any additional technical information.

Documentation (add "type: documentation" label)

feature_documentation

Testing notes:

1. start with this step
2. follow this step

[ynbot]

Task linked: OP-3426 Add support for Deadline for automatic tests

[iLLiCiTiT]

We should maybe have some function that would return True/False if is in testing mode instead of checking os.environ.get("IS_TEST") in each individual piece of code.

[iLLiCiTiT]

I would expect that argument --automatic_tests is flag that does not need a value.

EDITED: It should be also removed from sys.argv in start.py to cli does not have to handle it at all.

[kalisp]

How could I highlight that there is an 'automatic_tests' argument available for commands? (It is actually applicable only for some commands, even I cannot see why it shouldn't be on all commands, it just won't make any sense there.)