fix(plugin-vue): allow disabling transformAssetUrls

[bluwy]

Description

In Astro, it has its own image handling that returns image imports as an object, rather than a string. This would break when Vue automatically transform asset reference to imports.

However, when we try to disable with transformAssetUrls: false, it didn't work due to the logic flow, and always enabled it anyways. This PR fixes it.

There is a workaround today (withastro/astro#9328 (comment)), but I figured it's better to improve this anyway.

Additional context

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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.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[yoyo837]

Can this be merged?