Fix BestPossibleExternalViewVerifier for WAGED resource

[MarkGaox]

Issues

• My PR addresses the following Helix issues and references them in the PR description:
  BestPossibleExternalViewVerifier Fails to Accurately Verify WAGED Resources Due to Incomplete Cluster State Consideration #2938

Description

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Fix the bug where BestPossibleExternalViewVerifier fails to accurately verify WAGED resources. If the user has requested the WAGED resources, the verifier should run against the resources of whole cluster. We can achieve it by _resources.clear().

Tests

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The current test should be enough to capture this.

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Code Quality

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[MarkGaox]

PR approved by @xyuanlu. TFTR. Commit message: Fix BestPossibleExternalViewVerifier for WAGED resource