[ESLint] Update default .eslintrc file created to have .json format

[housseindjirdeh]

Fixs #26857. Update default .eslintrc file created to have .json format (.eslintrc without a file format is not on the list of supported configuration file formats)

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
buildDuration	13.2s	12.9s	-299ms
buildDurationCached	3.3s	3.1s	-131ms
nodeModulesSize	49.3 MB	49.3 MB	⚠️ +22 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.293	2.419	⚠️ +0.13
/ avg req/sec	1090.4	1033.32	⚠️ -57.08
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.338	1.278	-0.06
/error-in-render avg req/sec	1868.53	1955.69	+87.16

Client Bundles (main, webpack, commons)

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
359.HASH.js gzip	3.09 kB	3.09 kB	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	20.2 kB	20.2 kB	✓
webpack-HASH.js gzip	1.49 kB	1.49 kB	✓
Overall change	66.9 kB	66.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
polyfills-HASH.js gzip	31.1 kB	31.1 kB	✓
Overall change	31.1 kB	31.1 kB	✓

Client Pages

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
_app-HASH.js gzip	803 B	803 B	✓
_error-HASH.js gzip	3.18 kB	3.18 kB	✓
amp-HASH.js gzip	526 B	526 B	✓
css-HASH.js gzip	329 B	329 B	✓
hooks-HASH.js gzip	903 B	903 B	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.65 kB	1.65 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
withRouter-HASH.js gzip	320 B	320 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	8.42 kB	8.42 kB	✓

Client Build Manifests

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
_buildManifest.js gzip	390 B	390 B	✓
Overall change	390 B	390 B	✓

Rendered Page Sizes

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
index.html gzip	523 B	523 B	✓
link.html gzip	535 B	535 B	✓
withRouter.html gzip	515 B	515 B	✓
Overall change	1.57 kB	1.57 kB	✓

---

Webpack 4 Mode (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
buildDuration	11.7s	11.3s	-363ms
buildDurationCached	4.6s	4.4s	-130ms
nodeModulesSize	49.3 MB	49.3 MB	⚠️ +22 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.325	2.293	-0.03
/ avg req/sec	1075.04	1090.38	+15.34
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.316	1.275	-0.04
/error-in-render avg req/sec	1899.06	1961.04	+61.98

Client Bundles (main, webpack, commons)

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
14.HASH.js gzip	3.11 kB	3.11 kB	✓
677f882d2ed8..HASH.js gzip	13.4 kB	13.4 kB	✓
framework.HASH.js gzip	41.8 kB	41.8 kB	✓
main-HASH.js gzip	8.07 kB	8.07 kB	✓
webpack-HASH.js gzip	1.19 kB	1.19 kB	✓
Overall change	67.5 kB	67.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
polyfills-HASH.js gzip	31.3 kB	31.3 kB	✓
Overall change	31.3 kB	31.3 kB	✓

Client Pages

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
_app-HASH.js gzip	1.07 kB	1.07 kB	✓
_error-HASH.js gzip	3.83 kB	3.83 kB	✓
amp-HASH.js gzip	531 B	531 B	✓
css-HASH.js gzip	333 B	333 B	✓
hooks-HASH.js gzip	910 B	910 B	✓
index-HASH.js gzip	227 B	227 B	✓
link-HASH.js gzip	1.64 kB	1.64 kB	✓
routerDirect..HASH.js gzip	295 B	295 B	✓
withRouter-HASH.js gzip	292 B	292 B	✓
e025d2764813..52f.css gzip	125 B	125 B	✓
Overall change	9.26 kB	9.26 kB	✓

Client Build Manifests

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
_buildManifest.js gzip	418 B	418 B	✓
Overall change	418 B	418 B	✓

Rendered Page Sizes

	vercel/next.js canary	housseindjirdeh/next.js eslint-update-10	Change
index.html gzip	567 B	567 B	✓
link.html gzip	580 B	580 B	✓
withRouter.html gzip	559 B	559 B	✓
Overall change	1.71 kB	1.71 kB	✓

Commit: 4b90d43