refactor: deprecate billing_id and project_id in entitlement and usag…

[whoAbhishekSah]

Summary

Deprecate billing_id and project_id parameters in entitlement and usage RPCs. These fields will now be automatically inferred from org_id on the backend.

Changes

Marked the following fields as deprecated:

• CheckFeatureEntitlementRequest: billing_id, project_id
• CreateBillingUsageRequest: billing_id, project_id
• RevertBillingUsageRequest: billing_id, project_id

Usage

Clients should now only provide org_id when calling these RPCs:

• CheckFeatureEntitlement
• CreateBillingUsage
• RevertBillingUsage

The backend will automatically infer the billing account ID from the organization ID.