Use jinja2.pass_context instead of contextfilter

The contextfilter decorator was deprecated in jinja2 3.0.0, and has been
dropped in 3.1.0. This results in the following warning, and failed
attempts to use filters:

    [WARNING]: Skipping plugin (networks.py) as it seems to be invalid:
    module 'jinja2' has no attribute 'contextfilter'

This change switches to use the pass_context decorator. The minimum
version of Jinja2 is raised to 3 to ensure pass_context is present.

This change also includes some changes to address issues with image
builds in CI, caused by CentOS Scream.

1. disable IPA image builds in seed deploy jobs

IPA image builds will be split out into a separate job. For now, disable
them.

2. disable overcloud host image builds in seed deploy jobs

Overcloud host image builds will be split out into a separate job. For
now, disable them.

Depends-On: https://review.opendev.org/c/openstack/kayobe/+/835279
Change-Id: If657bf5b0117812d3c53942464cc41cf86cc8ad5