fix: Allow GraphQL query to non-installed images (#2250)

This pull request is a follow-up of #2136.

It has been observed that the `images(is_installed: Boolean)` GraphQL queries would fail to query `images(is_installed: false)` due to:
https://github.com/lablup/backend.ai/blob/05da1590095a61677402211cc84e74a07340b276/src/ai/backend/manager/models/gql.py#L1175-L1176

**Checklist:** (if applicable)

- [x] Milestone metadata specifying the target backport version
- [x] Mention to the original issue
- [ ] Installer updates including:
  - Fixtures for db schema changes
  - New mandatory config options
- [ ] Update of end-to-end CLI integration tests in `ai.backend.test`
- [ ] API server-client counterparts (e.g., manager API -> client SDK)
- [ ] Test case(s) to:
  - Demonstrate the difference of before/after
  - Demonstrate the flow of abstract/conceptual models with a concrete implementation
- [ ] Documentation
  - Contents in the `docs` directory
  - docstrings in public interfaces and type annotations

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📚 Documentation preview 📚: https://sorna--2250.org.readthedocs.build/en/2250/

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📚 Documentation preview 📚: https://sorna-ko--2250.org.readthedocs.build/ko/2250/

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changes/2250.fix.md

@@ -0,0 +1 @@
+Fix GraphQL to support query to non-installed images

src/ai/backend/manager/models/gql.py

@@ -1130,7 +1130,7 @@ async def resolve_images(
         root: Any,
         info: graphene.ResolveInfo,
         *,
-        is_installed=None,
+        is_installed: bool | None = None,
         is_operation=False,
         image_filters: list[str] | None = None,
     ) -> Sequence[Image]:
@@ -1173,7 +1173,7 @@ async def resolve_images(
         else:
             raise InvalidAPIParameters("Unknown client role")
         if is_installed is not None:
-            items = [item for item in items if item.installed]
+            items = [item for item in items if item.installed == is_installed]
         return items
 
     @staticmethod