fix: remove derived testIDs

[k0ndee]

Motivation

Many components generated "derived" testIDs by appending a hardcoded suffix to the user-supplied testID prop (e.g. ${testID}-container, ${testID}-outer-layer, ${testID}-text) so that tests could reach into internal, non-public parts of a component's render tree.

This PR removes every derived testID suffix from the library and updates the corresponding tests to assert public, user-visible behavior instead (accessible role/label/text queries, or the component's own real interactive element's testID). Where a check was genuinely about an internal implementation detail with no public equivalent (e.g. which of Surface's two iOS shadow layers a style lands on, or an in-flight animated value), the test was converted to a full render (toJSON()) snapshot instead of reaching into a specific internal node. Tests that turned out to assert nothing observable once the derived testID was gone were removed.

Affected components: Surface, Button, IconButton, CrossFadeIcon, Appbar (AppbarHeader, AppbarContent), ProgressBar, Chip, ListItem, Card, FAB (Content, Shell, Menu), SegmentedButtonItem, CheckboxItem, DataTableCell, Searchbar, Snackbar, Banner, ToggleButton, Menu/MenuItem, Modal, Dialog, DrawerCollapsedItem, BottomNavigation/BottomNavigationBar.

Related issue

None. This is an internal contributor task.

Test plan

• yarn jest — full suite passes (55 suites, 729 tests, 299 snapshots).
• yarn eslint src — no violations (including testing-library/no-node-access and the repo's no-restricted-syntax rule against raw .props access).
• yarn typecheck — no type errors.
• Snapshot diffs were reviewed to confirm each one only drops a removed testID line, with no unrelated structural or style changes.
• No UI/visual changes — this is a test-only and internal-prop-only change; component render output is otherwise identical (aside from the removed testID attributes themselves).