Exclude srcset from svg image

[styfle]

The default behavior for svg is dangerouslyAllowSVG: false which means we won't try to optimize the image because its vector (see #34431 for more).

However, svg was incorrectly getting the srcset attribute assigned which would contain duplicate information like:

/test.svg 1x, /test.svg 2x

So this PR makes sure we treat svg the same as unoptimized: true, meaning there is no srcset generated. Note that this PR won't change the behavior if loader is defined or if dangerouslyAllowSVG: true.

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
buildDuration	34.8s	34.3s	-537ms
buildDurationCached	14.6s	9.5s	-5s
nodeModulesSize	95 MB	95 MB	✓
nextStartRea..uration (ms)	273ms	285ms	⚠️ +12ms

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
152-HASH.js gzip	64.5 kB	64.5 kB	✓
53.HASH.js gzip	182 B	182 B	✓
main-app-HASH.js gzip	205 B	205 B	✓
main-HASH.js gzip	79.2 kB	79.2 kB	✓
webpack-HASH.js gzip	1.7 kB	1.7 kB	✓
Overall change	146 kB	146 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
_app-HASH.js gzip	192 B	192 B	✓
_error-HASH.js gzip	179 B	179 B	✓
amp-HASH.js gzip	484 B	484 B	✓
css-HASH.js gzip	804 B	804 B	✓
dynamic-HASH.js gzip	2.29 kB	2.29 kB	✓
edge-ssr-HASH.js gzip	255 B	255 B	✓
head-HASH.js gzip	827 B	827 B	✓
hooks-HASH.js gzip	848 B	848 B	✓
image-HASH.js gzip	4.29 kB	4.29 kB	✓
index-HASH.js gzip	252 B	252 B	✓
link-HASH.js gzip	2.69 kB	2.69 kB	✓
routerDirect..HASH.js gzip	782 B	782 B	✓
script-HASH.js gzip	857 B	857 B	✓
withRouter-HASH.js gzip	781 B	781 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	15.6 kB	15.6 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
_buildManifest.js gzip	482 B	482 B	✓
Overall change	482 B	482 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
index.html gzip	490 B	490 B	✓
link.html gzip	505 B	505 B	✓
withRouter.html gzip	485 B	485 B	✓
Overall change	1.48 kB	1.48 kB	✓

Edge SSR bundle Size Overall increase ⚠️

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
edge-ssr.js gzip	110 kB	110 kB	✓
page.js gzip	98.4 kB	98.4 kB	⚠️ +1 B
Overall change	209 kB	209 kB	⚠️ +1 B

Middleware size Overall increase ⚠️

	vercel/next.js canary	vercel/next.js styfle/next-321-nextimage-should-not-add-srcset-to-svg	Change
middleware-b..fest.js gzip	584 B	585 B	⚠️ +1 B
middleware-r..fest.js gzip	145 B	145 B	✓
middleware.js gzip	27 kB	27 kB	✓
edge-runtime..pack.js gzip	1.83 kB	1.83 kB	✓
Overall change	29.6 kB	29.6 kB	⚠️ +1 B

Commit: 951edd0