LU-16751 conf: remove outdated config files

LU-16751 conf: remove outdated config files

Remove the example modules.conf. This config file isn't really
specific to Lustre, and it very outdated regardless.

The remaining conf files (lustre.dtd, lustre2ldif.xsl, top.ldif)
were added ~15 years ago. They don't appear to account for the
changes in Lustre in the interim. It would be better to remove
them.

Also, update .gitignore.

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: Ia96eaac0a57c4b65c98d4b7931c96b344d7abd56
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51150
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>