Fix graph customdata for pointnumbers

[nickmelnikov82]

Fix #1663 - clickData for graph pie charts has pointNumbers but not customdata.

Contributor Checklist

• I have broken down my PR scope into the following TODO tasks
  • Fix issue
  • Make test
• I have run the tests locally and they passed. (refer to testing section in contributing)
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

optionals

• I have added entry in the CHANGELOG.md
• If this PR needs a follow-up in dash docs, community thread, I have mentioned the relevant URLS as follows
  • this GitHub #PR number updates the dash docs
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[alexcjohnson]

💃 Lovely fix, and excellent test! I'm preparing for a release now, will add a changelog entry for this as I do that.