selinux: set proc_uid_time_in_state type for /proc/uid

/proc/uid/ provides the same per-uid time_in_state data as
/proc/uid_time_in_state, so apply the same type and let system_server
read directories of this type.

Bug: 66953705
Test: system_server can read /proc/uid/*/time_in_state files without
denials on sailfish
Change-Id: Iab7fd018c5296e8c0140be81c14e5bae9e0acb0b
Signed-off-by: Connor O'Brien <connoro@google.com>