Fix regression in win_timezone.get_zone

[lukasraska]

What does this PR do?

Fixes regression introduced into win_timezone.get_zone which failed to report valid timezone if it begins or ends with one of _,d,s,t,o,f characters.

I've also moved whole unit test for win_timezone to pytest.

What issues does this PR fix or reference?

Fixes: #60829

Previous Behavior

$ c:/salt/salt-call.bat --local timezone.get_zone
local:
    Unknown

New Behavior

$ c:/salt/salt-call.bat --local timezone.get_zone
local:
    Europe/Kiev

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

[lukasraska]

The lint check failure seem unrelated to my changes:

************* Module salt.engines.junos_syslog
salt/engines/junos_syslog.py:95: [E0611(no-name-in-module), ] No name 'internet' in module 'twisted'
salt/engines/junos_syslog.py:96: [E0611(no-name-in-module), ] No name 'internet' in module 'twisted'