Enable default functional document when concurrentFeatures is enabled

[huozhi]

Bug

Fixes: #31675

Functional document without gIP should be enabled when streaming is enabled, even without rsc

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
buildDuration	25.1s	25.1s	⚠️ +11ms
buildDurationCached	4.7s	4.5s	-193ms
nodeModulesSize	346 MB	346 MB	⚠️ +619 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.203	4.043	-0.16
/ avg req/sec	594.76	618.34	+23.58
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.167	2.134	-0.03
/error-in-render avg req/sec	1153.56	1171.32	+17.76

Client Bundles (main, webpack, commons)

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28.4 kB	28.4 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.2 kB	72.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
_app-HASH.js gzip	1.37 kB	1.37 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	326 B	326 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	635 B	635 B	✓
image-HASH.js gzip	4.45 kB	4.45 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.87 kB	1.87 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.3 kB	13.3 kB	✓

Client Build Manifests

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
index.html gzip	532 B	532 B	✓
link.html gzip	546 B	546 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
buildDuration	27.2s	27.8s	⚠️ +625ms
buildDurationCached	4.5s	4.5s	-55ms
nodeModulesSize	346 MB	346 MB	⚠️ +619 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.218	4.164	-0.05
/ avg req/sec	592.75	600.42	+7.67
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.063	2.263	⚠️ +0.2
/error-in-render avg req/sec	1211.88	1104.73	⚠️ -107.15

Client Bundles (main, webpack, commons)

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.6 kB	28.6 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.5 kB	72.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.37 kB	2.37 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.47 kB	4.47 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	1.91 kB	1.91 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.2 kB	13.2 kB	✓

Client Build Manifests

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	huozhi/next.js fix/functional-doc	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	525 B	525 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: b72ad3a