feat: revert add .npmignore to rootfiles (#1642)

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## PR Checklist

- [ ] Addresses an existing open issue: fixes #000
- [ ] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/create-typescript-app/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [ ] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/create-typescript-app/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

<!-- Description of what is changed and how the code change does that.
-->
It turns out that `.npmignore` is not required as TSUP is handling this
on our behalf. And we don't publish `src` because we're not monsters

Author: johnnyreilly

.npmignore

@@ -25,7 +25,6 @@ export async function createRootFiles(options: Options) {
 				"node_modules/",
 			]),
 		}),
-		".npmignore": `*.test.*\n`,
 		".nvmrc": `20.12.2\n`,
 		".prettierignore": formatIgnoreFile([
 			...(options.excludeAllContributors ? [] : [".all-contributorsrc"]),