Mediawiki teardown publisher

Execute the slave script mw-teardown.sh after builds that installed a
sqlite database.  Will reclaim disk space on the tmpfs which tends to
fill up when too many builds are run at the same time on the same
slave.

I have compared the XML output to ensure jobs having mw-install-sqlite
also have mw-teardown using:

colordiff -u <(fgrep -l mw-teardown *) <(fgrep -l mw-install-sqlite *)

Bug: 71128
Change-Id: I603dc7414ad91168302702b31e2298753981dc4e