HAT: remove addencoding directives that are harmful on apache 2.4

As shown by bug #73274, any wiki page ending in .Z would result in an
incorrect Content-encoding header, so we plainly remove those
directives.

The only place where I can see this being maybe problematic is on
commons maybe? but plain non-image files are served by swift anyway, so
this should really be ok.

Change-Id: Ie9157e541311ba0614c712f50fb6908a37fc5fa5
Signed-off-by: Giuseppe Lavagetto <glavagetto@wikimedia.org>