[accordion] Remove deprecated props

[silviuaavram]

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

Removes accordion deprecated props, the changes are done by agent.

[mui-bot]

Netlify deploy preview

• docs/data/material/migration/upgrade-to-v9/upgrade-to-v9.md

Bundle size report

Bundle	Parsed size	Gzip size
@mui/material	▼-84B(-0.02%)	▼-55B(-0.04%)
@mui/lab	0B(0.00%)	0B(0.00%)
@mui/system	0B(0.00%)	0B(0.00%)
@mui/utils	0B(0.00%)	0B(0.00%)

Details of bundle changes

Generated by 🚫 dangerJS against b3474b2

[Copilot]

Pull request overview

Removes previously-deprecated Accordion transition customization props (TransitionComponent, TransitionProps) as part of the v9 API surface, standardizing on the slots/slotProps customization model.

Changes:

• Remove TransitionComponent / TransitionProps from Accordion implementation, TS types, PropTypes, and API docs.
• Update Accordion tests to use slots.transition / slotProps.transition.
• Document the breaking removal in the v9 upgrade guide.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/mui-material/src/Accordion/Accordion.js	Removes legacy transition props wiring and PropTypes entries.
packages/mui-material/src/Accordion/Accordion.d.ts	Removes legacy transition props from the public TypeScript API.
packages/mui-material/src/Accordion/Accordion.test.js	Migrates tests from legacy props to slots/slotProps.
docs/pages/material-ui/api/accordion.json	Removes legacy props from generated API docs JSON.
docs/data/material/migration/upgrade-to-v9/upgrade-to-v9.md	Adds v9 migration notes for the removed props.

Comments suppressed due to low confidence (1)

packages/mui-material/src/Accordion/Accordion.test.js:252

• Now that the legacy TransitionComponent/TransitionProps props are removed, it would be good to add a regression test asserting they are not forwarded to the DOM (e.g., rendering <Accordion TransitionComponent={...} /> should not set a TransitionComponent attribute on the root). This will catch accidental reintroductions of React unknown-prop warnings while still allowing apps to upgrade incrementally.

  describe('slotProps.transition', () => {
    it('should apply properties to the Transition component', () => {
      render(
        <Accordion slotProps={{ transition: { 'data-testid': 'transition-testid' } }}>
          {minimalChildren}
        </Accordion>,
      );

      expect(screen.getByTestId('transition-testid')).not.to.equal(null);

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[ZeeshanTamboli]

Link accordion-props codemod here like https://master--material-ui.netlify.app/material-ui/migration/upgrade-to-v9/#deprecated-apis-removed which is for Autocomplete.