fix(datetime): clear button clears the selected date

[sean-perkins]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
  • Some docs updates need to be made in the ionic-docs repo, in a separate PR. See the contributing guide for details.
• Build (npm run build) was run locally and any changes were pushed
• Lint (npm run lint) has passed locally and any fixes were made for failures

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

When clicking the "Clear" button, while the active month has a selected date, will not clear the active selected day.

Issue URL: #26258

What is the new behavior?

• The "Clear" button will clear the active selected date, clearing the active parts.

Does this introduce a breaking change?

• Yes
• No

Other information

Dev-build: 6.3.7-dev.11668105872.16a97bcc