Bump garden-ci-ubuntu to 0.11.9
Bump garden-ci-ubuntu to 0.11.9

[#156648201]

Signed-off-by: Georgi Sabev <cd7643e50243a10153b49cb72b4bdbf8b48cb045@gmail.com>

cloudfoundry-incubator/garden,cloudfoundry-incubator/garden