strongswan: Use user 'vpn'

This patches change the user name used for strongswan daemons
(charon, particulally) to 'vpn'. This is part of the effort to
unify uids used by different vpn clients.

BUG=b:191259955, b:177984585
TEST=manually verify charon is started as 'vpn' user

Cq-Depend: chromium:2972334, chromium:2972335
Change-Id: I5cb2605c5b25dc6219f7cfb969f1f4c7ffc88c60
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/2972185
Tested-by: Taoyu Li <taoyl@chromium.org>
Reviewed-by: Hugo Benichi <hugobenichi@google.com>
Reviewed-by: Jie Jiang <jiejiang@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Garrick Evans <garrick@chromium.org>
Commit-Queue: Taoyu Li <taoyl@chromium.org>
2 files changed