Improve test tooling (#18259)

## Summary

Unifies test mocking tooling across Jest and Storybook, replaces
handcrafted mock data with auto-generated server-fetched data, and
restructures the mock data generation script for maintainability.

### Mock data generation

- Split `generate-mock-data.ts` into three focused modules under
`scripts/mock-data/`:
  - `utils.ts` — shared authentication, GraphQL client, and file writer
  - `generate-metadata.ts` — fetches object metadata from `/metadata`
- `generate-record-data.ts` — fetches record data from `/graphql` using
metadata-driven dynamic queries
- The orchestrator (`generate-mock-data.ts`) authenticates once and
passes the token to both generators
- Company records are now fetched from the actual server (limited to 10
records) instead of being handcrafted
- Generated files are organized under `generated/metadata/objects/` and
`generated/data/companies/`

### Unified test utilities

- Consolidated Jest and MSW mocking into shared utilities that compose
production code (`prefillRecord`, `getRecordNodeFromRecord`,
`getRecordConnectionFromRecords`) with mock metadata
- Renamed `generateEmptyJestRecordNode` → `generateMockRecordNode` and
moved to `testing/utils/`
- Extracted `generateMockRecordConnection` into its own file
- Removed `sanitizeInputForPrefill` workaround (no longer needed with
correctly shaped generated data)

packages/twenty-front/src/modules/object-record/graphql/record-gql-fields/utils/__tests__/__snapshots__/generateActivityTargetGqlFields.test.ts.snap

@@ -1,4 +1,4 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
 exports[`generateActivityTargetGqlFields snapshot tests should match snapshot for Note with loadRelations="activity" 1`] = `
 {