request #6569 - Broken hooks symlinks after upgrade to gitolite3

*    remove gitolite-hooked and post-receive.mirrorpush hooks because they are not relevant anymore

Change-Id: I89e0666348b979255e11ed461a65daa820432358
Merge commit 'refs/changes/80/2180/2' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  request #6569 - Broken hooks symlinks after upgrade to gitolite3

Change-Id: Icd90325a7c219ca789095f178e64f45404a00ec5
This is Tuleap 6.11.99.34

Change-Id: I51c6d382961263ba70ca9c6fbce6df61477c2c4e