Fix cron module logic regarding working from non-root user

[Oloremo]

What does this PR do?

Fix cron module\state execution in case of Salt running from non-root user

What issues does this PR fix or reference?

Fixes #51872

Previous Behavior

cron state trying to run commands using the privilege escalation via runas arg in different modules.

New Behavior

If the current Salt process owner UID equals specified user in cron state it won't do a privilege escalation.

Tests written?

No

Commits signed with GPG?

Yes

[garethgreenaway]

@Oloremo Thanks for the PR. I think it might make more sense to break out the other if...else situations as you did for the raw_cron function in the others, to ensure that the Solaris/AIX functionality remains consistent.

[Oloremo]

@garethgreenaway I felt like I didn't break any logic and raw_cron func is just a bit different from the other, but if you like I can make them in the same style

[Oloremo]

Ok, so I tried to do some unification of the logic and updated tests according to it.
Problem is now I have new kind of condition which isn't covered by tests - when I check if salt running from a root user:

_check_instance_uid_match('root'):

And I'm not sure how to mock it properly to test this condition.

The second problem I hesitated to remove the final else and commented it with
# Edge cases here, let's try do a runas but in fact, I'm pretty sure that if the user hit this condition - it will result in an error since it's not the same user and not the root user so in that case we probably don't have enough permissions to do this operation anyway.

[Oloremo]

@garethgreenaway mind to look at this PR again?