Accept password authentication in addition to public key authentication,
but ignore the actual password, so that clients without ssh keys
configured (or configured to send no ssh keys) can authenticate.
Change-Id: I86130b9725d1928ac45b5db55f18c09687ee0fd5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3807
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>