Drop the V2 suffix from the core workspace ORM classes (#24774)

## What

Third of the five PRs splitting #24759 (after #24761 and #24768). With
the files already in place from the paths-only move, this drops the `V2`
suffix from the core classes. Pure identifier renames, no file moves:

- `WorkspaceRepositoryV2` → `WorkspaceRepository` (and the
`workspaceRepositoryV2` properties)
- `WorkspaceSelectQueryBuilderV2` → `WorkspaceSelectQueryBuilder`,
`WorkspaceMutationQueryBuilderV2` → `WorkspaceMutationQueryBuilder`
- `WorkspaceDataSourceV2` → `WorkspaceDataSource`,
`WorkspaceDataSourceV2Service` → `WorkspaceDataSourceService` (name
freed by the `WorkspaceSchemaService` rename in #24761)
- `QueryExecutorV2` → `QueryExecutor`

Review rule: the diff is +229/−229 across 55 files and every hunk swaps
exactly one of these identifier pairs.

## Notes for CI

One committed upgrade command (the 2-22 person-avatar migration) gets a
type-annotation rename only, so the PR carries the
`ci:allow-previous-version-upgrade-mutation` label.

## Coming next

The manager and module rename (`GlobalWorkspaceOrmManager` →
`WorkspaceOrmManager`, `GlobalWorkspaceDataSourceModule` →
`TwentyOrmModule`), then the internal leftovers.

## Verification

- `tsgo --noEmit` clean, `oxlint --type-aware` clean on the 54 changed
files, `oxfmt --check src/` clean
- All twenty-orm unit suites pass (405 tests)


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