ESM backport importlib fix to released focal branch

[blackboxsw]

CPC is looking to sync changes to ESM images for importlib errors seen on Pro images.
Backport upstream fix a97e746 as a quilt patch to ensure both focal and bionic get the destination patch.

Proposed Commit Message

Separate commits

* releasing cloud-init version 24.4.1-0ubuntu0~20.04.3+esm2

* fix: import specific importlib.util avoiding traces in pro auto-attach
    
    Use direct submodule import of importlib.util to avoid AttributeError
    tracebacks from ua-auto-attach.service on GCE.
    
    Backport-of: a97e7466
    Fixes GH-6924

Additional Context

As this is an ESM fix, this release will be reviewed by security team to be included in ESM infra PPA instead of typical Ubuntiu SRU process.
This upstream fix will make it into LTS releases via typical SRU process.

Test Steps

quilt push -a  # patches apply

lxc launch ubuntu-minimal:focal f-min
lxc exec f-min -- pro attach <YOUR_TOKEN>
lxc exec f-min -- apt install ubuntu-pro-client cloud-init
lxc file push cloudinit/importer.py f-min/usr/lib/python3/dist-packages/cloudinit/
lxc exec f-min -- python3 /usr/lib/ubuntu-advantage/auto_attach.py   # confirm no traceback
quilt pop -a    # patched removed without issue

PPA for testing https://launchpad.net/~chad.smith/+archive/ubuntu/esm-backport-testing

Merge type

• Squash merge using "Proposed Commit Message"
• Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)
• git merge from command line after approval.