Remove redundant domain_realm mappings

This fixes a long-standing documentation bug where we claimed that
a domain_realm mapping for a host name would not affect entries
under that domain name.  The code has always had the behavior where
a host name mapping implies the corresponding domain name mapping,
since the 1.0 release.

While here, replace media-lab with csail in example files, as the
media lab realm is no longer in use.  Also strip port 88 from KDC
specifications, and drop the harmful default_{tgs,tkt}_enctypes
lines from src/util/profile/krb5.conf.

Further cleanup on these files to remove defunct realms may be in order.

ticket: 7690 (new)
tags: pullup
target_version: 1.11.4