hotfix: zkEVM under maintenance banner

[ayumitk]

Pull Request Summary

• Added zkEVM under maintenance banner for all networks

Check list

• [ ] contains breaking changes
• [ ] adds new feature
• [x] modifies existing feature (bug fix or improvements)
• [ ] relies on other tasks
• [ ] documentation changes
• [ ] tested on mobile devices

This pull request makes the following changes:

Adds

• (ex: Add feature A)

Fixes

• (ex: Fix validation function)

Changes

• (ex: Change document B)

To-dos

*Feel free to remove this section if it's not applicable

• [ ] (ex: add user list)

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit d08f13f):

https://astar-apps--pr1260-hotfix-under-mainten-05udtrzu.web.app

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[Kahonnohak]

@ayumitk its for release-hotfix branch, then we should be able to merge