test: temporarily skip the EnterNamespace= test w/o embedded debuginfo

test: temporarily skip the EnterNamespace= test w/o embedded debuginfo

The EnterNamespace= feature currently doesn't work if the debuginfo is
separated from the crashing binary. Until that's resolved, let's run the
test only if the test binary has embedded debuginfo (.debug_info
section; e.g. when systemd is built without WITH_DEBUG=1) or it contains
MiniDebugInfo (.gnu_debugdata section; default on Fedora and CentOS).

See: https://github.com/systemd/systemd/pull/39268#issuecomment-3390745718
(cherry picked from commit 80b4cacf1b121c8b1ec444970cc566dc4efd1837)