Avoid executing commands from path

[mackdk]

What does this PR change?

This PR uses absolute paths when invoking commands to avoid using the PATH environment variable and thus avoid being subjected to possible environment injection attacks.

GUI diff

No difference.

• [X] DONE

Documentation

• No documentation needed: only internal and user invisible changes

• [X] DONE

Test coverage

• No tests: already covered

• [X] DONE

Links

Issue(s): https://github.com/SUSE/spacewalk/issues/24387

• [X] 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"

Before you merge

Check How to branch and merge properly!