Remove vitest globals (#21505)

Explicitly import them instead which is cleaner and enables better
editor integration.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/js/features/repo-findfile.test.js

@@ -1,3 +1,4 @@
+import {describe, expect, test} from 'vitest';
 import {strSubMatch, calcMatchedWeight, filterRepoFilesWeighted} from './repo-findfile.js';
 
 describe('Repo Find Files', () => {

web_src/js/svg.test.js

@@ -1,3 +1,4 @@
+import {expect, test} from 'vitest';
 import {svg} from './svg.js';
 
 test('svg', () => {

web_src/js/utils.test.js

@@ -1,3 +1,4 @@
+import {expect, test} from 'vitest';
 import {
   basename, extname, isObject, uniq, stripTags, joinPaths, parseIssueHref,
   prettyNumber, parseUrl,