Fix non-doctest documentation tests

[blnicho]

Summary

Several of our online documentation pages include code snippets that are "literal included" from doc/OnlineDocs/tests. This directory has a test driver script, test_examples.py, which is meant to test these code snippets that aren't being tested using the standard Sphinx doctest infrastructure. However, it doesn't look like we're running these tests in any of our automated testing infrastructure. Furthermore, the test_examples.py script is a modified copy of the book test driver which was rewritten in #1914.

We need to:

• Update test_examples.py following the changes in examples/pyomobook/test_book_examples.py
• Get the tests passing again
• Make sure the tests are being run on GitHub Actions

Information on your system

Pyomo version: main branch
Python version: all
Operating system: all
How Pyomo was installed (PyPI, conda, source): source
Solver (if applicable):