Moved mhvtl's tape to tmpfs.

This makes the system tests faster on HDD backed systems as mhvtl is an heavy user of fsync.

Fsync cost can go up to 100ms on HDD (+vm + hyperV).

continuousintegration/buildtree_runner/recreate_buildtree_running_environment.sh

@@ -8,9 +8,11 @@ echo Wiping mhvtl and kubernetes library info...
 systemctl stop mhvtl || true
 sleep 2
 rm -rf /etc/mhvtl
+umount /opt/mhvtl || true
 rm -rf /opt/mhvtl
 rm -rf /opt/kubernetes/CTA/library
 mkdir -p /opt/mhvtl
+mount -t tmpfs -o size=512m tmpfs /opt/mhvtl
 
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 ### puppet:///modules/hg_cta/00-cta-tape.rules