/etc/apparmor.d/usr.lib.dovecot.dovecot-auth is in apparmor-profiles 2.7.103-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | # Author: Kees Cook <kees@ubuntu.com>
#include <tunables/global>
/usr/lib/dovecot/dovecot-auth flags=(complain) {
  #include <abstractions/authentication>
  #include <abstractions/base>
  #include <abstractions/nameservice>
  #include <abstractions/wutmp>
  capability setgid,
  capability chown,
  capability dac_override,
  /proc/*/mounts r,
  /usr/lib/dovecot/dovecot-auth mr,
  /{,var/}run/dovecot/** rw,
  # required for postfix+dovecot integration
  /var/spool/postfix/private/dovecot-auth w,
  # Site-specific additions and overrides. See local/README for details.
  #include <local/usr.lib.dovecot.dovecot-auth>
}
 |