This reverts the bundler change part while we investigate source map
issue but keeps the externals optimize preventing the runtime bundle
from inflating back to over `4MB`.
This reverts commit 98b0700e97
This reverts commit 04c3f0b29c
This improves the build script quite a bit and makes dev editing much
faster. Also fixed excludes causing webpack/babel compiled packages to
be bundled into the runtime un-necessarily reducing from `10MB` ->
`1.2MB`.
Before: `Finished next_bundle in 9.67s`
After: `Finished next_bundle in 1.27s`
Validated here
https://github.com/vercel/vercel/actions/runs/12957911052/job/36147343396?pr=12914
Observable in `pnpm next dev test/development/app-dir/dynamic-io-dev-errors/` and `/no-accessed-data`. It only affects the bottom stacks in that particular stack so assertions are not viable yet until the full stack is properly sourcemapped.
Janka Uryga