parse virtual-host-gatherer null value (#7282)

[mbussolotto]

What does this PR change?

parse virtual-host-gatherer null value

GUI diff

No difference.

• DONE

Documentation

• No documentation needed: add explanation. This can't be used if there is a GUI diff

• No documentation needed: only internal and user invisible changes

• Documentation issue was created: Link for SUSE Manager contributors, Link for community contributors.

• API documentation added: please review the Wiki page Writing Documentation for the API if you have any changes to API documentation.

• (OPTIONAL) Documentation PR

• DONE

Test coverage

• No tests: already covered

• Unit tests were added

• DONE

Links

• DONE

Changelogs

Make sure the changelogs entries you are adding are compliant with https://github.com/uyuni-project/uyuni/wiki/Contributing#changelogs and https://github.com/uyuni-project/uyuni/wiki/Contributing#uyuni-projectuyuni-repository

If you don't need a changelog check, please mark this checkbox:

• No changelog needed

If you uncheck the checkbox after the PR is created, you will need to re-run changelog_test (see below)

Re-run a test

If you need to re-run a test, please mark the related checkbox, it will be unchecked automatically once it has re-run:

• Re-run test "changelog_test"
• Re-run test "backend_unittests_pgsql"
• Re-run test "java_pgsql_tests"
• Re-run test "schema_migration_test_pgsql"
• Re-run test "susemanager_unittests"
• Re-run test "javascript_lint"
• Re-run test "spacecmd_unittests"

[github-actions]

Suggested tests to cover this Pull Request

• srv_virtual_host_manager
• buildhost_docker_auth_registry
• srv_menu
• buildhost_docker_build_image
• buildhost_osimage_build_image