LU-6179 llite: remove LOCKAHEAD_OLD compatibility

The OBD_CONNECT_LOCKAHEAD_OLD feature was added for a short time for
compatibility with an implementation of LDLM lockahead that was later
replaced by OBD_CONNECT_LOCKAHEAD2.

Remove the compatibility code for this old implementation that has
been disabled since the 2.13 release.

Also remove other obsolete compatibility code dating back to 2.8.53.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I4444eff180b2c6e2b27d260413f2debbb2ce7057
Reviewed-on: https://review.whamcloud.com/38109
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>