bump fly
add BOSH_LITE_IP param for testflight
atc check interval is configurable
bump testflight
remove garden-linux-release submodule

now consuming and testing against their releases directly in ci. yay!

from now on, when final releases are shipped, the example manifests will
point to the garden-linux release that it was vetted against, by url and
by version.

[#79446810]