feat: clear more Mocha and Jest remnants (#1607)

## PR Checklist

- [x] Addresses an existing open issue: fixes #1372; fixes #1373; fixes
#1374
- [x] 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)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/create-typescript-app/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Cleans up existing files and file properties related to them.

💖

Author: JoshuaKGoldberg

src/steps/clearUnnecessaryFiles.ts

@@ -3,6 +3,7 @@ import * as fs from "node:fs/promises";
 const globPaths = [
 	...extensions(".babelrc", "cjs", "cts", "js", "json", "mjs"),
 	...extensions(".eslintrc", "js", "json", "yml"),
+	...extensions(".mocha", "cjs", "js", "json", "jsonc", "yaml", "yml"),
 	...extensions(".prettierrc", "json", "json5", "yaml", "yml"),
 	...extensions("prettier.config", "js", "mjs", "cjs"),
 	...extensions("babel.config", "cjs", "cts", "js", "json", "mjs"),

src/steps/writing/creation/writePackageJson.ts

@@ -55,6 +55,8 @@ export async function writePackageJson(options: Options) {
 		// Remove fields we know we don't want, such as old or redundant configs
 		eslintConfig: undefined,
 		husky: undefined,
+		jest: undefined,
+		mocha: undefined,
 		prettierConfig: undefined,
 		types: undefined,