Fix invalid regex pattern in ValidatorUtils

[RamsaiPolisetti]

This PR fixes a malformed regex pattern in ValidatorUtils.

The previous regex was incomplete due to missing quantifier and closing token,
causing incorrect context-path validation.

Updated:

• Corrected CONTEXT_PATH_MATCH pattern
• Verified successful compilation with: ./mvnw -DskipTests=true install

This resolves incorrect path validation and restores proper client behavior.

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[github-actions]

Thanks for your this PR. 🙏
Please check again for your PR changes whether contains any usage/api/configuration change such as Add new API , Add new configuration, Change default value of configuration.
If so, please add or update documents(markdown type) in docs/next/ for repository nacos-group/nacos-group.github.io

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感谢您提交的PR。 🙏
请再次查看您的PR内容，确认是否包含任何使用方式/API/配置参数的变更，如：新增API、新增配置参数、修改默认配置等操作。
如果是，请确保在提交之前，在仓库nacos-group/nacos-group.github.io中的docs/next/目录下添加或更新文档（markdown格式）。

[KomachiSion]

I can't get the reason of this PR.