i965: Emit texture cache invalidates around blorp_copy

This is a terrible hack but it fixes CTS regressions.  It's still
incredibly unclear exactly what is going wrong in the hardware to cause
this to be an issue so this isn't a good fix by any means.  However, it
does fix tests so there is that.

Fixes: fb0e9b51 "i965: Track the depth and render caches separately"
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103746


Acked-by: Kenneth Graunke <kenneth@whitecape.org>
(cherry picked from commit 8379bff6)