v3: alarm: ansible: Fix version timestamp

ansible_date_time.iso8601 includes : in the time fields, which is not
great including in filenames. This used to be ok, until we discovered
that chrome likes to silently rename our files.

Let's strftime our own format to something similar to the iso, but
use _ instead of :

TEST=sudo ansible-playbook -i inventory.yml *play.yml -vvv --skip-tags chroot --tags ansible_log
TASK [get date and git describe] *******************************
...
    "stdout": "2024-04-04T17_31_58Z-v3-270-ga3313b8-dirty",
BUG=b/327280083

Change-Id: I5df33cab61f1a7539ba8021f715f39382ed4998e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/5425851
Tested-by: Alexandru Stan <amstan@chromium.org>
Auto-Submit: Alexandru Stan <amstan@chromium.org>
Commit-Queue: Michał Barnaś <barnas@google.com>
Reviewed-by: Michał Barnaś <barnas@google.com>
1 file changed