examples: remove next-env.d.ts files

[JamBalaya56562]

Summary

Remove next-env.d.ts file from the examples directory because gitignore template includes them.

Description

At #41041, removed next-env.d.ts files.
However, #47241 reintroduced them.

create-next-app makes next-env.d.ts file in the example directory if it's typescript.

next.js/packages/create-next-app/create-app.ts

Lines 202 to 209 in c2078d0

	// Copy `next-env.d.ts` to any example that is typescript
	const tsconfigPath = join(root, 'tsconfig.json')
	if (existsSync(tsconfigPath)) {
	copyFileSync(
	getTemplateFile({ template, mode: 'ts', file: 'next-env.d.ts' }),
	join(root, 'next-env.d.ts')
	)
	}

Therefore, next-env.d.ts file isn't necessary.

CC: @samcx

Adding or Updating Examples

• The "examples guidelines" are followed from our contributing doc https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
• Make sure the linting passes by running pnpm build && pnpm lint. See https://github.com/vercel/next.js/blob/canary/contributing/repository/linting.md

[ijjk]

Allow CI Workflow Run

• approve CI run for commit: 8bdefc1

Note: this should only be enabled once the PR is ready to go and can only be enabled by a maintainer

[JamBalaya56562]

Thank you for approving this PR!

CI was failed because some .gitignore files didn't include next-env.d.ts.
I updated them and ran pnpm lint-no-typescript && pnpm check-examples without any errors.

So could you run CI one more time?