Change customized stoppable check log level

[MarkGaox]

Issues

• My PR addresses the following Helix issues and references them in the PR description:
  N/A

Description

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  This PR changes the log level to DEBUG so the stoppable end won't generate excessive logs when the customized stoppable check json response is massive.

Tests

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  N/A

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Commits

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Code Quality

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[MarkGaox]

The PR is approved by @xyuanlu and is ready to merge. The failed CI is an known issue #2967
Final commit message: Change customized stoppable check log level