Tests: disable some tests on Alt Linux due to rpm config

On Alt Linux, some tests that rely on debuginfo and/or rpm
config (using buildroot related binary `brp-alt`), can not succeed.
They produce errors like "package do not have URL as expected",
"source_package-buildroot: No such file or directory", and
"non-stripped binaries don't contain .debug sections".

These tests are disabled by this commit in case of `brp-alt` found.