copr-builder: remove mirrors.fp.o ~ proxy01 alias so that we don't rely on just a single proxy

historically proxy01 worked the best for us but now after
https://pagure.io/fedora-infrastructure/issue/7553, the situation
could be better.

alternative would be to use proxy01 and proxy10 which are both
in phx2 that would require something else than /etc/hosts alias.

roles/copr/backend/files/provision/provision_builder_tasks.yml

@@ -98,12 +98,6 @@
     regexp: '^%_install_lang.*'
     state: 'absent'
 
-- name: 'Point mirrors.fedoraproject.org to proxy01.fedoraproject.org, which is the closest proxy'
-  lineinfile:
-    dest: '/etc/hosts'
-    line: '209.132.181.16 mirrors.fedoraproject.org'
-    state: 'present'
-
 - name: 'debug for https://pagure.io/fedora-infrastructure/issue/7301'
   lineinfile:
     dest: '/etc/hosts'