Comment 4 for bug 1953610

[Test Plan]
To reproduce the issue, use the annotated steps below. Confirmed working as a reproducer for Focal and Impish. Bionic appears to use a -data package instead of building the db on "apt update"

Notes:
1) The "ubuntu" user below is unprivileged, the result of the "adduser ubuntu" command being run and accepting defaults.
2) The "lck" and "ack" commands were randomly selected as commands that were unavailable on the default Ubuntu images used by LXD.

# Confirm UMASK
grep "^UMASK" /etc/login.defs
# Set /etc/login.defs to umask 027
sed -i -e 's/^UMASK\t\t022/UMASK\t\t027/' /etc/login.defs
# Confirm
grep "^UMASK" /etc/login.defs
# Log out and back in
exit

# Log back in
# Force rebuild of DB
rm -rf /var/lib/command-not-found/*
apt update
ls -lah /var/lib/command-not-found/
# Verify failure
su - ubuntu
lck
ack
exit
## END repro

The failures expected to be seen when running the "lck" and "ack" commands are similar to:
ubuntu@lp1953610-focal:~$ ack
Sorry, command-not-found has crashed! Please file a bug report at:
https://bugs.launchpad.net/command-not-found/+filebug
Please include the following information with the report:

command-not-found version: 0.3
Python version: 3.8.10 final 0
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal
Exception information:

unable to open database file
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/CommandNotFound/util.py", line 23, in crash_guard
    callback()
  File "/usr/lib/command-not-found", line 90, in main
    cnf = CommandNotFound.CommandNotFound(options.data_dir)
  File "/usr/lib/python3/dist-packages/CommandNotFound/CommandNotFound.py", line 79, in __init__
    self.db = SqliteDatabase(dbpath)
  File "/usr/lib/python3/dist-packages/CommandNotFound/db/db.py", line 12, in __init__
    self.con = sqlite3.connect(filename)
sqlite3.OperationalError: unable to open database file

A successful run should look like:
ubuntu@lp1953610-focal:~$ lck

Command 'lck' not found, did you mean:

  command 'ack' from deb ack (3.3.1-1)
  command 'ick' from deb intercal (30:0.30-3)
  command 'lcp' from deb lsh-client (2.1-12build3)
  command 'lc' from deb mono-devel (6.8.0.105+dfsg-2)
  command 'lcf' from deb ucf (3.0038+nmu1)
  command 'ck' from deb python3-ck (1.9.4-1.1)

Try: apt install <deb name>