[autotest] disable chromeos2/hydra1 and enable chromeos4/hydra[12]

hydra1 in chromeos2 is very flaky. Disable it untill
b/17612645 is fixed.
Enable rpm support for duts behind hydra1,2 in chromeos4.

TEST=manually called the changed method with different hostnames.
BUG=chromium:392548,chromium:433400,chromium:433402
CQ-DEPEND=CL:229858

Change-Id: Ib8f50d307eeba0fc9af1276735851e4f5139e5d8
Reviewed-on: https://chromium-review.googlesource.com/229862
Reviewed-by: Prashanth B <beeps@chromium.org>
Commit-Queue: Fang Deng <fdeng@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
1 file changed