enter_chroot: Fix ownership of /run/user/UID
enter_chroot: Fix ownership of /run/user/UID

We were chowning the host directory, not the one in the chroot.

Host gpg >= 2.1.13 puts the gpg-agent socket in /run/user/UID/gnupg,
which is bind-mounted into the chroot, but the SDK gpg was ignoring it
because /run/user/UID was not owned by UID. This broke tag signing with
YubiKeys.

coreos/scripts,glevand/coreos--scripts,coreos/scripts,glevand/coreos--scripts