Remove get_var('PUBLIC_CLOUD') in faver of version_utils::is_public_cloud()

[pdostal]

[github-actions[bot]]

Great PR! Please pay attention to the following items before merging:

Files matching lib/**.pm:

• [ ] Consider adding or extending unit tests in t/

This is an automatically generated QA checklist based on modified files.

[asmorodskyi]

A lot of places was a big surprise for me . What is_public_cloud is even doing there . But it is not related to this PR . Just a note for myself that I would like to investigate this PR later ...

[asmorodskyi]

I may ignore trigger_and_monitor_openqa but not "Running unit tests with perl v5.32 (pull_request) " can you please figure out what is going on https://github.com/os-autoinst/os-autoinst-distri-opensuse/actions/runs/8733773597/job/23963113904?pr=18793

[pdostal]

I may ignore trigger_and_monitor_openqa but not "Running unit tests with perl v5.32 (pull_request) " can you please figure out what is going on https://github.com/os-autoinst/os-autoinst-distri-opensuse/actions/runs/8733773597/job/23963113904?pr=18793

I'm clueless 😞 I asked @mpagot.

[mpagot]

I may ignore trigger_and_monitor_openqa but not "Running unit tests with perl v5.32 (pull_request) " can you please figure out what is going on https://github.com/os-autoinst/os-autoinst-distri-opensuse/actions/runs/8733773597/job/23963113904?pr=18793

I'm clueless 😞 I asked @mpagot.

Issue is not only in Unit Testing: look at https://github.com/os-autoinst/os-autoinst-distri-opensuse/actions/runs/8733773376/job/23963113237?pr=18793#step:5:14 --> https://openqa.opensuse.org/tests/4091612

[2024-04-18T07:06:24.327234Z] [warn] [pid:86367] !!! main: "is_public_cloud" is not exported by the version_utils module
  Can't continue after import errors at /var/lib/openqa/pool/16/os-autoinst-distri-opensuse/lib/Utils/Backends.pm line 21.
  BEGIN failed--compilation aborted at /var/lib/openqa/pool/16/os-autoinst-distri-opensuse/lib/Utils/Backends.pm line 21.
  Compilation failed in require at /var/lib/openqa/pool/16/os-autoinst-distri-opensuse/lib/version_utils.pm line 13.
  BEGIN failed--compilation aborted at /var/lib/openqa/pool/16/os-autoinst-distri-opensuse/lib/version_utils.pm line 13.
  Compilation failed in require at /var/lib/openqa/pool/16/os-autoinst-distri-opensuse/products/opensuse/main.pm line 12.
  BEGIN failed--compilation aborted at /var/lib/openqa/pool/16/os-autoinst-distri-opensuse/products/opensuse/main.pm line 12.
  Compilation failed in require at /usr/lib/os-autoinst/OpenQA/Isotovideo/Utils.pm line 390.