fix(scheduler): extend ambient host-account UUID tagging to Azure/GCP collectors (sibling of #604)

[cristim]

PR #607 (closed #604) tagged AWS recommendation rows with the registered host-account UUID instead of nil on the ambient-credentials fallback path in collectAWSRecommendations. The PR kept the change AWS-only as scoped and noted that the Azure and GCP collectors (collectAzureRecommendations, collectGCPRecommendations) have the same ambient-fallback shape, deferred to a follow-up that was never filed.

Scope:

• Verify whether collectAzureRecommendations and collectGCPRecommendations exhibit the same nil-host-account-on-ambient-fallback behavior fixed for AWS in fix(scheduler/aws): tag rec rows with registered host-account UUID instead of nil when only ambient AWS account is configured #604.
• If confirmed, extend the host-account tagging fix to those collectors.

Out of scope when deferred: PR #607 was scoped to the AWS collector to keep blast radius tight.

Deferred by: #607
Related: #604 (AWS fix).

[cristim]

Verified shipped on feat/multicloud-web-frontend via PR #725 (merged 2026-05-27). Azure and GCP collectRecommendations paths now tag rows with the registered host-account UUID on the ambient-credentials fallback, matching the AWS fix in PR #607.