No-op update of Scaling settings changes minReplicas from null to 0

[v-ruizh]

OS: Win 11 x64
Build Version: 20260609.1

Repro Steps:

1. Create an Azure Container App.
2. Expand the above container app -> Right-click Scaling node and select "View Properties".
3. Verify that the configuration contains: "minReplicas": null.
4. Expand the Scaling node and observe that it displays Min / max replicas: 0 / 10.
5. Right-click the Scaling node and select "Edit Scaling Range...".
6. Without making any changes, press Enter to save and deploy.
7. After deployment completes, right-click Scaling node and select "View Properties" again.

Expect:
No configuration changes should be applied when the user does not modify any scaling values. The property should remain: "minReplicas": null.

Actual:
The property is changed to "minReplicas": 0 even though no user changes were made.

More Info:

1. UI default value (0) is treated as user input during save.
2. Leads to unintended configuration mutation.
3. Breaks distinction between unset (null) and explicit (0) values.