Deprecate EventDetection.times

[stephprince]

Summary of changes

Following discussion related to #555 and #619, EventDetection.times stores duplicate information as the source_idx and there are currently no checks that the two agree with each other. Since there are minimal example usages of EventDetection on DANDI, it may be best to deprecate this dataset.

Checklist

For all schema changes:

• Add release notes for the PR to docs/format/source/format_release_notes.rst.
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.
• Make sure that hdmf-common-schema points to the latest release and not the latest commit on the main branch.

If this is the first schema change after a schema release (i.e., the version string in core/nwb.namespace.yaml does not
end in "-alpha"), then:

• Update the version string in core/nwb.namespace.yaml and core/nwb.file.yaml to the next major/minor/patch
  version with the suffix "-alpha". For example, if the current version is 2.4.0 and this is a minor change, then the
  new version string should be "2.5.0-alpha".
• Update the value of the version variable in docs/format/source/conf.py to the next version without the
  suffix "-alpha", e.g., "2.5.0".
• Update the value of the release variable in docs/format/source/conf.py to the next version with the suffix
  "-alpha", e.g., "2.5.0-alpha".
• Add a new section in the release notes docs/format/source/format_release_notes.rst for the new version
  with the date "Upcoming" in parentheses.