vfs: fix lint warnings in router.js and test-vfs-chdir.js

Remove blank lines between JSDoc description and @param tags
(jsdoc/tag-lines) and remove unused `common` variable assignment
(no-unused-vars).

Author: mcollina

lib/internal/vfs/router.js

@@ -22,7 +22,6 @@ const { isAbsolute, relative, sep } = require('path');
  * handles root mount points like 'C:\' on Windows, where the mount point
  * already ends with a backslash. Without this check, appending another
  * separator would produce 'C:\\' which would never match any path.
- *
  * @param {string} normalizedPath A normalized absolute path
  * @param {string} mountPoint A normalized mount point path
  * @returns {boolean}
@@ -56,7 +55,6 @@ function isUnderMountPoint(normalizedPath, mountPoint) {
  * A simpler `StringPrototypeSlice(normalizedPath, mountPoint.length)` would
  * work on POSIX but would produce '\src\index.js' on Windows (with a leading
  * backslash and backslash separators), which the provider cannot look up.
- *
  * @param {string} normalizedPath A normalized absolute path
  * @param {string} mountPoint A normalized mount point path
  * @returns {string} The relative path (starting with /)

test/parallel/test-vfs-chdir.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const common = require('../common');
+require('../common');
 const assert = require('assert');
 const fs = require('fs');
 const os = require('os');