fix: use plugin:markdown/recommended-legacy (#1381)

## PR Checklist

- [x] Addresses an existing open issue: fixes #1380
- [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

Switches to the `recommended-legacy` plugin and bumps
`eslint-plugin-markdown` to the latest version, 4.x.

Author: JoshuaKGoldberg

Diff for: .eslintrc.cjs

@@ -25,7 +25,7 @@ module.exports = {
 	ignorePatterns: ["!.*", "coverage*", "lib", "node_modules", "pnpm-lock.yaml"],
 	overrides: [
 		{
-			extends: ["plugin:markdown/recommended"],
+			extends: ["plugin:markdown/recommended-legacy"],
 			files: ["**/*.md"],
 			processor: "markdown/markdown",
 		},

Diff for: package.json

@@ -76,7 +76,7 @@
 		"eslint-plugin-eslint-comments": "^3.2.0",
 		"eslint-plugin-jsdoc": "^48.0.0",
 		"eslint-plugin-jsonc": "^2.10.0",
-		"eslint-plugin-markdown": "^3.0.1",
+		"eslint-plugin-markdown": "^4.0.1",
 		"eslint-plugin-n": "^16.3.1",
 		"eslint-plugin-package-json": "^0.10.0",
 		"eslint-plugin-perfectionist": "^2.5.0",

Diff for: pnpm-lock.yaml

@@ -25,7 +25,7 @@ exports[`expected file changes > .eslintrc.cjs 1`] = `
 +	ignorePatterns: ["!.*", "coverage", "lib", "node_modules", "pnpm-lock.yaml"],
  	overrides: [
  		{
- 			extends: ["plugin:markdown/recommended"],
+ 			extends: ["plugin:markdown/recommended-legacy"],
 @@ ... @@ module.exports = {
  			rules: {
  				// These off-by-default rules work well for this repo and we like them on.

Diff for: script/__snapshots__/migrate-test-e2e.js.snap

@@ -128,7 +128,7 @@ describe("createESLintRC", () => {
 				  ignorePatterns: ["!.*", "coverage", "lib", "node_modules", "pnpm-lock.yaml"],
 				  overrides: [
 				    {
-				      extends: ["plugin:markdown/recommended"],
+				      extends: ["plugin:markdown/recommended-legacy"],
 				      files: ["**/*.md"],
 				      processor: "markdown/markdown",
 				    },

Diff for: src/steps/writing/creation/createESLintRC.test.ts

@@ -35,7 +35,7 @@ module.exports = {
 			? ""
 			: `
 		{
-			extends: ["plugin:markdown/recommended"],
+			extends: ["plugin:markdown/recommended-legacy"],
 			files: ["**/*.md"],
 			processor: "markdown/markdown",
 		},`