Skip Windows cloud DSN setup when cloud tests are disabled

[slabko]

Summary

Follow-up to #589. Windows still configured cloud DSNs unconditionally, even when the cloud tests were skipped. With unavailable secrets, this passes an empty Password= property to Add-OdbcDsn, causing the DSN setup step to fail.

• Move both cloud DSNs into a dedicated step guarded by the same cloud-enabled, Release, and x64 conditions as database creation and cloud tests.
• Keep local DSN setup and DSN listing unconditional.

Validation

• Parsed the updated workflow as YAML.
• Checked all 8 combinations of cloud availability, build type, and architecture.
• Verified all six DSN commands are preserved and other existing steps are unchanged.
• git diff --check passed.
• Windows execution remains to be verified by CI.