Rename the legacy schema service and fold the v2 ORM module (#24761)

## What

First of the five PRs splitting #24759 (kept closed as reference), which
itself was the last third of #24745. Two tiny preparatory changes with
no ORM behavior content:

- **Rename the legacy `WorkspaceDataSourceService` to
`WorkspaceSchemaService`.** The service in `engine/workspace-datasource`
is the pre-v1 schema-lifecycle layer (create and delete the workspace
Postgres schema, plus a raw query used by the two remaining legacy
repositories). Renaming it frees the natural
`WorkspaceDataSourceService` name for the v2 datasource service, which
picks it up when the suffixes drop in a later PR of this sequence.
- **Fold `TwentyORMV2Module` into `GlobalWorkspaceDataSourceModule`.**
Its only provider was `WorkspaceDataSourceV2Service`; the global module
(which already imported it) now provides and exports the service
directly, and the three feature modules that imported the v2 module drop
the import.

## Coming next (in sequence, each after the previous merges)

1. Move `twenty-orm-v2/` into `twenty-orm/`, paths only, no identifier
changes.
2. Drop the `V2` suffix from the core classes (repository, query
builders, datasource, executor).
3. Rename `GlobalWorkspaceOrmManager` to `WorkspaceOrmManager` and the
module to `TwentyOrmModule`.
4. Rename the internal leftovers (find-option types, contexts, group-by
service, README sweep).

## Verification

- `tsgo --noEmit` clean, `oxlint --type-aware` and `oxfmt --check src/`
clean
- Schema-service and scoped-repository unit suites pass
- Behavior neutral: a class rename and a module fold with identical
providers


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