Enable shared worker pool by default

[ijjk]

This enables the shared worker pool for static page generation by default and also moves the staticPageGenerationTimeout config out of experimental.

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
buildDuration	13s	13.1s	⚠️ +57ms
buildDurationCached	3.1s	3.2s	⚠️ +109ms
nodeModulesSize	195 MB	195 MB	-55 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.057	3.236	⚠️ +0.18
/ avg req/sec	817.69	772.47	⚠️ -45.22
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.459	1.38	-0.08
/error-in-render avg req/sec	1713.86	1811.06	+97.2

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
651.HASH.js gzip	2.96 kB	2.96 kB	✓
831.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	26.1 kB	26.1 kB	✓
webpack-HASH.js gzip	1.49 kB	1.49 kB	✓
Overall change	73 kB	73 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
_app-HASH.js gzip	979 B	979 B	✓
_error-HASH.js gzip	3.06 kB	3.06 kB	✓
amp-HASH.js gzip	551 B	551 B	✓
css-HASH.js gzip	329 B	329 B	✓
dynamic-HASH.js gzip	2.67 kB	2.67 kB	✓
head-HASH.js gzip	2.32 kB	2.32 kB	✓
hooks-HASH.js gzip	918 B	918 B	✓
image-HASH.js gzip	5.87 kB	5.87 kB	✓
index-HASH.js gzip	260 B	260 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	319 B	319 B	✓
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	19.8 kB	19.8 kB	✓

Client Build Manifests

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
_buildManifest.js gzip	492 B	492 B	✓
Overall change	492 B	492 B	✓

Rendered Page Sizes

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
index.html gzip	548 B	548 B	✓
link.html gzip	560 B	560 B	✓
withRouter.html gzip	542 B	542 B	✓
Overall change	1.65 kB	1.65 kB	✓

---

Default Build with SWC (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
buildDuration	6.2s	6.2s	-74ms
buildDurationCached	3.1s	2.9s	-238ms
nodeModulesSize	195 MB	195 MB	-55 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.119	3.146	⚠️ +0.03
/ avg req/sec	801.54	794.69	⚠️ -6.85
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.454	1.442	-0.01
/error-in-render avg req/sec	1719.71	1733.21	+13.5

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
450.HASH.js gzip	179 B	179 B	✓
675-HASH.js gzip	13.9 kB	13.9 kB	✓
framework-HASH.js gzip	50.8 kB	50.8 kB	✓
main-HASH.js gzip	36.5 kB	36.5 kB	✓
webpack-HASH.js gzip	1.64 kB	1.64 kB	✓
Overall change	103 kB	103 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
_app-HASH.js gzip	1.33 kB	1.33 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	315 B	315 B	✓
css-HASH.js gzip	330 B	330 B	✓
dynamic-HASH.js gzip	2.79 kB	2.79 kB	✓
head-HASH.js gzip	356 B	356 B	✓
hooks-HASH.js gzip	638 B	638 B	✓
image-HASH.js gzip	556 B	556 B	✓
index-HASH.js gzip	262 B	262 B	✓
link-HASH.js gzip	2.22 kB	2.22 kB	✓
routerDirect..HASH.js gzip	325 B	325 B	✓
script-HASH.js gzip	390 B	390 B	✓
withRouter-HASH.js gzip	322 B	322 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	10.1 kB	10.1 kB	✓

Client Build Manifests

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
_buildManifest.js gzip	512 B	512 B	✓
Overall change	512 B	512 B	✓

Rendered Page Sizes

	vercel/next.js canary	ijjk/next.js update/shared-pool	Change
index.html gzip	547 B	547 B	✓
link.html gzip	560 B	560 B	✓
withRouter.html gzip	541 B	541 B	✓
Overall change	1.65 kB	1.65 kB	✓

Commit: da7b6c5