Fix process.env overriden in web runtime

[huozhi]

Fixes #31258

Bug

• 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/web-process-env	Change
buildDuration	18s	17.8s	-213ms
buildDurationCached	3.6s	3.5s	-81ms
nodeModulesSize	334 MB	334 MB	⚠️ +280 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	huozhi/next.js fix/web-process-env	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.952	2.9	-0.05
/ avg req/sec	846.79	862.01	+15.22
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.418	1.39	-0.03
/error-in-render avg req/sec	1762.48	1798.59	+36.11

Client Bundles (main, webpack, commons)

	vercel/next.js canary	huozhi/next.js fix/web-process-env	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28.2 kB	28.2 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.1 kB	72.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	huozhi/next.js fix/web-process-env	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/web-process-env	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	327 B	327 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	4.44 kB	4.44 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/web-process-env	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/web-process-env	Change
index.html gzip	522 B	522 B	✓
link.html gzip	535 B	535 B	✓
withRouter.html gzip	516 B	516 B	✓
Overall change	1.57 kB	1.57 kB	✓

---

Default Build with SWC (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	huozhi/next.js fix/web-process-env	Change
buildDuration	19.1s	19.2s	⚠️ +134ms
buildDurationCached	3.5s	3.5s	⚠️ +1ms
nodeModulesSize	334 MB	334 MB	⚠️ +280 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	huozhi/next.js fix/web-process-env	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.903	2.884	-0.02
/ avg req/sec	861.2	866.93	+5.73
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.401	1.374	-0.03
/error-in-render avg req/sec	1784.86	1818.84	+33.98

Client Bundles (main, webpack, commons)

	vercel/next.js canary	huozhi/next.js fix/web-process-env	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.4 kB	28.4 kB	✓
webpack-HASH.js gzip	1.43 kB	1.43 kB	✓
Overall change	72.4 kB	72.4 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	huozhi/next.js fix/web-process-env	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/web-process-env	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	2.38 kB	2.38 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.46 kB	4.46 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/web-process-env	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/web-process-env	Change
index.html gzip	522 B	522 B	✓
link.html gzip	534 B	534 B	✓
withRouter.html gzip	515 B	515 B	✓
Overall change	1.57 kB	1.57 kB	✓

Commit: afd0b1f