FreeRADIUS refuses a config dir that is globally writable; the kubelet
projected volume root is. Mount it at /etc/raddb-src, copy it into an
emptyDir with an initContainer and run radiusd from the copy. The test
harness now makes the mount world-writable and runs the initContainer
from the manifest.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>