NamespaceIsolationPolicies may need support priority

**Is your enhancement request related to a problem? Please describe.**
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current， if we have two Policies that match the same namespace。 which one will take effect is not certain.

**Describe the solution you'd like**
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add an `order` field in NamespaceIsolationData, to order them ,we
getPolicyByNamespace, we get the NamespaceIsolationPolicy which have the bigger order.

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**Additional context**
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Start by locating NamespaceIsolationData and the getPolicyByNamespace entry point, then trace how matching policies are currently selected. Confirm the intended meaning of a larger order value and identify the affected policy configuration and selection tests. Done means overlapping namespace policies have deterministic priority behavior and the behavior is covered by tests.

Written by the indexing model from the issue text.