fix: gcs-access-token endpoint error

Type of change

• Bug Fix
• Feature
• Pipeline
• Test
• Documentation

Does this introduce a change in the core logic?

• No
• Yes

Does this introduce a change in the cloud provider implementation, if so which cloud?

• AWS
• Anthos
• Azure
• GCP
• IBM

Does this follow conventional commits spec?

• No
• Yes

Have you set the target Milestone?

• No
• Yes

Have you set the no-detached-pipeline label?

• No
• Yes

Updates description?

There was 2 problems with /gcs-access-token endpoint

1. With dataset policy /gcs-token?sdpath=sd://tenant/subproject returned 200 but should have been 400
2. With uniform policy /gcs-token?sdapth=sd://tenant/subprpoject/dataset endpoint returned 400 but should have been 200