Decrease tests resource footprint on CI minion

Due to constrained CI minion resources docker volumes
need to be pruned after each test invocation to prevent
false negative which occurs in case when multiple playbook
level tests are run.

Heavy VNC Server image (1GB) needs to be mocked with
lightweight alpine image in play-infrastructure test
for same reasons.

Change-Id: I1026593a375853575cf210aefe29bc320d4e5c64
Signed-off-by: Bartek Grzybowski <b.grzybowski@partner.samsung.com>
Issue-ID: OOM-1907
2 files changed