[autotest] Add retry in install package inside container.

This is to alieviate the flake when running apt-get command.

BUG=chromium:499631
TEST=local lxc_functional_test.py

Change-Id: I0be1d9e305465bb73a5e8e1e5b2f4b57bd234f7d
Reviewed-on: https://chromium-review.googlesource.com/282331
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
1 file changed