ctdb-scripts: Remove 60.ganesha, replace with callout for 60.nfs

ctdb-scripts: Remove 60.ganesha, replace with callout for 60.nfs

This isn't a straightforward move of code from 60.ganesha to the
callout.  Simplifications have been made to allow better
interoperation with the new NFS checking logic.

The following configuration variables have been removed:

  CTDB_GANESHA_REC_SUBDIR

    Edit NFS ganesha callout to change this location

  CTDB_NFS_SERVER_MODE, NFS_SERVER_MODE

    Use CTDB_NFS_CALLOUT instead

  CTDB_NFS_SKIP_KNFSD_ALIVE_CHECK, CTDB_SKIP_GANESHA_NFSD_CHECK

    Disable the corresponding .check file instead

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>