VOL-5155 - triage failure in periodic-voltha-test-bbsim-2.12

.gitignore
----------
  o Ignore a.out and archives/ created late by the test target.

config.mk
makefiles/targets/sterile.mk
makefiles/targets/tox.mk
----------------------------
  o Update sterile target to remove the archives directory.
  o tox.mk updated to remove generated .tox/ directory.

jjb/pipeline/voltha/master/bbsim-tests.groovy
jjb/pipeline/voltha/voltha-2.12/bbsim-tests.groovy
--------------------------------------------------
  o Fixed a typo in the 'Combine and compress' banner.
  o In compress combined log block:
    - Display logs to compress.
    - '|| true' removed from gzip.  Wrap call with log collection
      and only invoke when logs are available (allow cmds to fail on err).

Change-Id: I141c0bbd1e8c946c652f00f21401bd897d8a4135
diff --git a/makefiles/targets/tox.mk b/makefiles/targets/tox.mk
index b3a638b..9d50962 100644
--- a/makefiles/targets/tox.mk
+++ b/makefiles/targets/tox.mk
@@ -28,6 +28,9 @@
 lint-tox: lint-jjb
 	tox -e py310
 
+sterile ::
+	$(RM) -r .tox#       # $(TOP)/.tox
+
 ## -----------------------------------------------------------------------
 ## -----------------------------------------------------------------------
 help-verbose += help-tox