Removes expected part of EXPECTED_ERRORS with a variety of changes.
- In many placed in the code, "expected" was used to mean
"ignored and expected", and all such instances are renamed to "ignored".
- The setting ``EXPECTED_ERRORS`` is renamed to ``IGNORED_ERRORS``,
which better matches how it was being used in the first place.
- The setting ``EXPECTED_ERRORS[REASON_EXPECTED]`` is renamed to ``IGNORED_ERRORS[REASON_IGNORED]``.
- The setting toggle ``EXPECTED_ERRORS[IS_IGNORED]`` is removed,
because it will now always be True.
- The how-to will is renamed to how_tos/logging-and-monitoring-ignored-errors.rst.
See 0002-logging-and-monitoring-expected-errors-removed.rst for more details.
Implements DEPR: https://github.com/openedx/edx-platform/issues/32405
**BREAKING CHANGE:** The rename of the setting ``EXPECTED_ERRORS`` to
``IGNORED_ERRORS``, and ``REASON_EXPECTED`` to ``REASON_IGNORED``,
was implemented without backward compatibility. Simply copy the old settings
with the new name as an expand phase before deleting the old names in the
contract phase.
d9af2dfb36