Revert "CI: add templated Dockerfiles to build logs"

This reverts commit 09c890b124.

Reason for revert: That change caused all Kolla's work items to be
transferred. This includes tarballs, their extracted contents, cloned
git repositories, etc. to also be transferred to swift which takes
extra time, pollutes logs and decreases the stability of jobs slightly
(the mechanism is not designed for this kind of load).
The collection of templated Dockerfiles in CI has to be reimplemented
if it is wanted.

Change-Id: Ideaf66ce18c993802f4d20f490caa47cec0dde5e

.zuul.d/base.yaml

@@ -113,7 +113,6 @@
     extra-vars:
       kolla_logs_dir: "{{ zuul_output_dir }}/logs/kolla"
       kolla_build_logs_dir: "{{ kolla_logs_dir }}/build"
-      kolla_work_dir: "{{ kolla_logs_dir }}"
       virtualenv_path: "/tmp/kolla-virtualenv"
 
 - job:

tests/playbooks/run.yml

@@ -13,7 +13,6 @@
         # NOTE(yoctozepto): to avoid issues with IPv6 not enabled in the docker daemon
         # and since we don't need isolated networks here, use host networking
         network_mode: host
-        work_dir: "{{ kolla_work_dir }}"
   tasks:
     - name: Ensure /etc/kolla exists
       file: