[date-pickers] Fix inconsistent invalid date for controlled date field

[siriwatknp]

Issue

Reproduction: https://stackblitz.com/edit/1kmt3frx?file=src%2FDemo.tsx

While checking #20040, I found another bug shown in the recording below.
The value return from onChange callback is swapping between null and invalid date.

Screen.Recording.2568-10-31.at.11.58.49.mov

Fix

It should check for previous invalid date, not valid.

Test added.

• I have followed (at least) the PR section of the contributing guide.

[mui-bot]

Deploy preview: https://deploy-preview-20158--material-ui-x.netlify.app/

Bundle size report

Bundle	Parsed size	Gzip size
@mui/x-data-grid	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-pro	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-premium	0B(0.00%)	0B(0.00%)
@mui/x-charts	0B(0.00%)	0B(0.00%)
@mui/x-charts-pro	0B(0.00%)	0B(0.00%)
@mui/x-charts-premium	0B(0.00%)	0B(0.00%)
@mui/x-date-pickers	▼-25B(-0.01%)	▼-12B(-0.02%)
@mui/x-date-pickers-pro	▼-27B(-0.01%)	▼-12B(-0.01%)
@mui/x-tree-view	0B(0.00%)	0B(0.00%)
@mui/x-tree-view-pro	0B(0.00%)	0B(0.00%)

Details of bundle changes

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