feat: add json-formatted event data to error logs

[rgraber]

Adds event_data_as_json to the error log when an event is not published. This will make it easier to recreate the event from the logs using an AvroSignalDeserializer.

Added the field instead of replacing the event data field so we will still get the event that was passed to the send method even if something in the serializer throws an error on creation. Also left everything else in the = format because Splunk is actually parsing them correctly as fields, it was just the nested event data it had trouble with.

To test, set up your event bus to point to the dev cluster but with an incorrect schema registry password. When trying to fire an event, you should see an error like
Error delivering message to Kafka event bus. error=Unauthorized (HTTP status code 401, SR code 401) full_topic='dev-graber-course-catalog-info-changed' event_key=CourseLocator('edX', 'DemoX', 'Demo_Course', None, None) signal=<OpenEdxPublicSignal: org.openedx.content_authoring.course.catalog_info.changed.v1> initial_topic='course-catalog-info-changed' event_key_field='catalog_info.course_key' event_data={'catalog_info': CourseCatalogData(course_key=CourseLocator('edX', 'DemoX', 'Demo_Course', None, None), name='Demonstration Course', schedule_data=CourseScheduleData(start=datetime.datetime(2013, 2, 5, 5, 0, tzinfo=<bson.tz_util.FixedOffset object at 0xffff58196b80>), pacing='instructor', end=None, enrollment_start=datetime.datetime(2013, 2, 5, 0, 0, tzinfo=<bson.tz_util.FixedOffset object at 0xffff58196b80>), enrollment_end=None), hidden=False, invitation_only=False)} event_metadata=EventsMetadata(event_type='org.openedx.content_authoring.course.catalog_info.changed.v1', id=UUID('065c50fe-3218-11ee-bfb5-0242ac15000c'), minorversion=0, source='openedx/cms/web', sourcehost='cms.devstack.edx', time=datetime.datetime(2023, 8, 3, 16, 8, 44, 784693, tzinfo=datetime.timezone.utc), sourcelib=(8, 3, 0)) event_data_as_json='{"catalog_info": {"course_key": "course-v1:edX+DemoX+Demo_Course", "hidden": false, "invitation_only": false, "name": "Demonstration Course", "schedule_data": {"end": null, "enrollment_end": null, "enrollment_start": "2013-02-05T00:00:00+00:00", "pacing": "instructor", "start": "2013-02-05T05:00:00+00:00"}}}'
(note the event_data_as_json field).

Merge checklist:
Check off if complete or not applicable:

• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Commits are squashed
• Noted any: Concerns, dependencies, deadlines, tickets, testing instructions

[timmc-edx]

I think we'll also want to reset this cache in _reset_caches at the end of the file.