apparmor: fix rule for /proc/*/task/*/comm

https://phabricator.apertis.org/T9494

apparmor-pipewire test currently fails with following AppArmor audit log:

# ====
# profile:/usr/bin/pipewire
# sdmode:REJECTING
# denied_mask:wr
# operation:open
# name:/proc/3070/task/3079/comm
# request_mask:wr

Signed-off-by: Dylan Aïssi dylan.aissi@collabora.com