support/testing: drop explicit docker kernel options from docker test

support/testing: drop explicit docker kernel options from docker test

Since commit 0390777bfaff6c6 (package/docker-engine: needs some kernel
options), docker-engine now automatically ensures the needed kernel options
are enabled, so drop the explicit options from the kernel config.

23:19:27 TestDockerCompose                        Starting
23:19:28 TestDockerCompose                        Building
00:14:41 TestDockerCompose                        Building done
00:15:30 TestDockerCompose                        Cleaning up
.
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Ran 1 test in 3362.784s

OK

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>