fix(server): seat not allocated when new user invited to licensed workspace (#12322)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **Bug Fixes**
  - Improved the accuracy of workspace member overcapacity calculation.
  - Corrected seat allocation handling for one-time license variants, ensuring proper event emission and bypassing unnecessary updates.

- **Refactor**
  - Streamlined internal logic by removing an obsolete method related to seat count checks.

- **Tests**
  - Removed a workspace member list pagination test to streamline end-to-end testing.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/core/quota/service.ts

@@ -144,8 +144,7 @@ export class QuotaService {
       : await this.getWorkspaceStorageUsage(workspaceId);
     const memberCount =
       await this.models.workspaceUser.chargedCount(workspaceId);
-    const overcapacityMemberCount =
-      await this.models.workspaceUser.insufficientSeatMemberCount(workspaceId);
+    const overcapacityMemberCount = memberCount - quota.memberLimit;
 
     return {
       ...quota,