investigate license issue with /actor-tests/src/test/bind/etc/ files

See https://lists.apache.org/thread/dv11y9f3sn388dw7tfdw22pkg3bq7tzs

The [bind.keys](https://github.com/apache/incubator-pekko/blob/main/actor-tests/src/test/bind/etc/bind.keys) file seems to be based on https://github.com/isc-projects/bind9/blob/main/bind.keys

There may be more files that have copies of code from https://github.com/isc-projects/bind9 (I haven't found other matches in a quick search)

We can't include Mozilla Public License code because it has copyleft implications.

Added in https://github.com/akka/akka/pull/25690