labstation: increase timeout in image_downloader

Due to the current test image size 15 mins timeout is not enough
anymore.

BUG=b:461376696
TEST=manual

Change-Id: I1799033987501bd869263c3c9092644e0c75d480
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/labstation/+/7168363
Reviewed-by: Garry Wang <xianuowang@chromium.org>
Commit-Queue: Jacek Klimkowicz <klimkowicz@google.com>
Auto-Submit: Jacek Klimkowicz <klimkowicz@google.com>
Tested-by: Jacek Klimkowicz <klimkowicz@google.com>
1 file changed