legacy: use Oxc for minify by default #21973

Description

plugin-legacy has been using terser for minification regardless of the value of build.minify because esbuild didn't support keeping the syntax as-is. Now that Oxc supports that, we can respect build.minify: 'oxc' and build.minify: true for it.

Suggested solution

Remove this line as some other places

We should make sure to add build.rolldownOptions.output.minify.compress.target.

Alternative

No response

Additional context

Originally suggested in #21858

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.