remove cmd-suite-option-for-hiding-admin-commands

Remove the incomplete and non-functional cmd option for hiding admin
commands, introduced in commit 36d02757fd6863a845163daf0d730bdcc0a28343.

This patch removes the CMD_ADMIN flag, the non-functional help -admin
parameter, and the non-functional cmd_IsAdministratorCommand() function.

Thanks to Jeffrey Altman for pointing out this old commit and for
suggestions on cleanup.

Change-Id: I72c7d2ed7109b1238713fe0d6d177c5af6fc6b7d
Reviewed-on: http://gerrit.openafs.org/11429
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Garrett Wollman <wollman@csail.mit.edu>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: D Brashear <shadow@your-file-system.com>