Remove un-used app-dir test fixture

[ijjk]

This fixture is not being used as we aren't currently able to test the ts plugin directly and will need to investigate using a headless vs code instance to test against.

x-ref: https://vercel.slack.com/archives/C04DUD7EB1B/p1672784680457859

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall decrease ✓

	vercel/next.js canary	ijjk/next.js tests/remove-unused-fixture	Change
buildDuration	35.7s	36s	⚠️ +308ms
buildDurationCached	10.3s	10.6s	⚠️ +304ms
nodeModulesSize	95.2 MB	95.2 MB	✓
nextStartRea..uration (ms)	282ms	278ms	-4ms

Client Bundles (main, webpack)

	vercel/next.js canary	ijjk/next.js tests/remove-unused-fixture	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	ijjk/next.js tests/remove-unused-fixture	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ijjk/next.js tests/remove-unused-fixture	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	2.27 kB	2.27 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	4.3 kB	4.3 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	ijjk/next.js tests/remove-unused-fixture	Change
_buildManifest.js gzip	482 B	482 B	✓
Overall change	482 B	482 B	✓

Rendered Page Sizes

	vercel/next.js canary	ijjk/next.js tests/remove-unused-fixture	Change
index.html gzip	489 B	489 B	✓
link.html gzip	504 B	504 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	ijjk/next.js tests/remove-unused-fixture	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 decrease ✓

	vercel/next.js canary	ijjk/next.js tests/remove-unused-fixture	Change
middleware-b..fest.js gzip	582 B	581 B	-1 B
middleware-r..fest.js gzip	145 B	145 B	✓
middleware.js gzip	27.1 kB	27.1 kB	✓
edge-runtime..pack.js gzip	1.83 kB	1.83 kB	✓
Overall change	29.7 kB	29.7 kB	-1 B

Commit: 6c15165