DataForm: Fix the datetime control sending two updates per calendar interaction

[ntsekouras]

What?

Fixes a bug noticed by @ciampo:
in the datetime control, selecting or clearing a date in the calendar sent two identical DataForm updates for a single user action — once directly and once in a timeout that also moved focus into the datetime input and back, to reveal validation errors.

It turns out without the previous duplicate update, ControlWithError revealed a stale or empty message, since it reads the input's validationMessage before the input has re-rendered with the new value. Instead of relying on the extra update, ControlWithError now re-reads the message when an invalid event is received.

Testing Instructions

There are unit tests for the calendar interactions, which they fail in trunk.

Note there's no visible difference from trunk in the steps below: trunk moved focus into the input and restored it too fast to notice, and this PR doesn't move it at all. What to check is that the behavior is preserved: the error still appears and the day button keeps focus in step 2.

1. npm run storybook:dev and open DataViews / DataForm → Validation.
2. Select a date in the Date time field's calendar, then click the same day again to clear it: the required error should appear under the input, and focus stays on the day button.

Use of AI Tools

Generated with Fable 5 and adjusted/reviewed manually.

[github-actions]

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Co-authored-by: ntsekouras <ntsekouras@git.wordpress.org>
Co-authored-by: jorgefilipecosta <jorgefilipecosta@git.wordpress.org>
Co-authored-by: ciampo <mciampini@git.wordpress.org>

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[github-actions]

Size Change: +112 B (0%)

Total Size: 7.71 MB

📦 View Changed

Filename	Size	Change
build/scripts/block-editor/index.min.js	458 kB	+29 B (+0.01%)
build/scripts/components/index.min.js	256 kB	+16 B (+0.01%)
build/scripts/edit-site/index.min.js	333 kB	+1 B (0%)
build/scripts/editor/index.min.js	530 kB	+44 B (+0.01%)
build/scripts/media-utils/index.min.js	153 kB	+22 B (+0.01%)

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[jorgefilipecosta]

Nit: the control only schedules 0 ms timeouts, so I guess the 10 ms sleep is arbitrary. Could we use 0 ms here (or fake timers) so the test does not rely on a magic number? Harmless as-is.

[ntsekouras]

I think 10 is fine (upper bound) because while we could use 0 ms to catch duplicates at the same tick, the slightly bigger timeout could catch cases with a slightly later timeout. I agree 10 is still arbitrary and could update if you want. I don't have strong opinions on this 😄

[github-actions]

Flaky tests detected in c566d2f.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/31575557755
📝 Reported tests:

redirects revision deep links to the classic screen in /test/e2e/specs/editor/various/revisions.spec.js, passed after 1 failed attempt.

Error: apiRequestContext.fetch: socket hang up
Call log:
  - → POST http://localhost:8889/wp-json/wp/v2/posts
    - user-agent: Playwright/1.62.1 (x64; ubuntu 24.04) node/20.20 CI/1
    - accept: */*
    - accept-encoding: gzip,deflate,br
    - X-WP-Nonce: ead88556e9
    - content-type: application/json
    - content-length: 126
    - cookie: wordpress_test_cookie=WP%20Cookie%20check; wordpress_logged_in_23778236db82f19306f247e20a353a99=admin%7C1786694013%7CQv9OTj02xYDCoY9J8xESxOm7WQoWh2CRGZBgMHKGhaO%7C7eb1cbd5ada48f7d4380accc375955438c3e8bf63192382a4c3df3776e2720e5; wp-settings-time-1=1786522059

    at RequestUtils.rest (/home/runner/work/gutenberg/gutenberg/packages/e2e-test-utils-playwright/src/request-utils/rest.ts:112:39)
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/revisions.spec.js:457:35