Fix link to external minio endpoint

Description:

Fixed minIO external endpoint link for creating signed URL  

How to test:

1. Get storage instructions using storage service (/storageInstructions?kindSubType=dataset--File.Generic)
2. Upload the file using the link from the storage instructions.
3. Register the file in the dataset (/registerDataset)

Repeat for 1000 files in 20 threads. Expected result: signet URL include minIO external endpoint link.  

Changes include:

• Bugfix (a non-breaking change that solves an issue).  

Changes in:

• GCP