fix(optimizer): suppress esbuild cancel error

[bluwy]

Description

When esbuildContext.rebuild() is called, then esbuildContext.cancel() is called, esbuild logs an error, which we don't want as we're intentionally cancelling the build. This PR checks the error message and suppresses it.

Additional context

This should fix the logs appearing in Astro's ecosystem-ci unit tests, since the unit test runs server restarts consecutively, triggering this error. Though even with the error logs, the test passes, but this change should help avoid confusion.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the PR Title Convention.
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• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
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[patak-dev]

Nice!