Remove events from the API/SDK, an Event is now a LogRecord with the EventName field set

[DylanRussell]

Description

See open-telemetry/opentelemetry-specification#4045 and open-telemetry/opentelemetry-specification#4319 - the event API and SDK are deprecated in the spec.

The only change made to support events is adding the event name field to the LogRecord. If you want to emit an event you can do so using the logging API/SDK using a LogRecord with the event_name field set. This simplifies the code a bunch and aligns python with the spec and what other languages do.

I have another PR (#4645) out to update the proto version ahead of v1.5 which added event_name to the LogRecord, and to add the event_name field to the LogRecord API/SDK.

Type of change

Please delete options that are not relevant.

• [x ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

Unit tests. This change is deleting code only.

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• [x ] No.

Checklist:

• [ x] Followed the style guidelines of this project
• [ x] Changelogs have been updated
• [ x] Unit tests have been added
• [ x] Documentation has been updated

[DylanRussell]

Ok there are 4 broken instrumentations we have to update first..

First #4645 needs to get submitted, so we can start putting EventName directly into the LogRecord instead of as an attribute.

Then we have to go and update the instrumentations to emit a LogRecord with the event name set instead of using the events API..

Then we can make this change..