next-swc-napi: Remove "plugin" from default feature list (#66380)
Effectively a revert of https://github.com/vercel/next.js/pull/66006,
but:
- Keeps the cleanup changes from that PR.
- With https://github.com/vercel/nextpack/pull/106 removing the explicit
`--features plugin` flag, we will match behavior between cargo's
defaults and the nextpack development scripts (which we want to do for
maximizing cache reuse).
The tradeoff here is faster cold builds, at the cost of waiting longer
when you want to test with plugins.
Feedback from @kdy1 was:
> I think it's a good idea to disable plugin by default for nextpack. We
don't use it for most of daily development, but it's very large and slow
to compile
Tested by running both:
```
pnpm build-native
pnpm build-native-no-plugin
```