INTMDB-334: privatelink endpoint service configurable timeout

[evertsd]

Description

Users hit timeout during GCP PSC setup. Default timeout has been updated to 2 hours & made configurable via terraform.

Type of change:

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update
• [x] Documentation fix/enhancement

Required Checklist:

• [x] I have signed the MongoDB CLA
• [x] I have read the Terraform contribution guidelines
• [ ] I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• [x] I have added any necessary documentation (if appropriate)
• [x] I have run make fmt and formatted my code

Further comments