refactor(frontend): remove stale reload method call on `/admin/users` page

[zyoshoka]

What

/admin/users ページに残っている不要なメソッド呼び出しを削除します。

Why

https://github.com/misskey-dev/misskey/commit/5c5d3c1a240f2b8175d773f084916e38ec2a61bb#diff-2ef64414b49d081dda4ce08eeced24033bcf5e4f36091700964a89b43be1fcc6L39-R39 の際に書き換え変え忘れたからか、入力欄を更新した際にコンソールに次のようなエラーが出るようになっている上に、別になくても更新されるため

[Vue warn]: Error in https://vuejs.org/error-reference/#runtime-6: "TypeError: can't access property "reload", i.$refs.users is undefined"

Additional info (optional)

Checklist

• [x] Read the contribution guide
• [x] Test working in a local environment
• [ ] (If needed) Add story of storybook
• [ ] (If needed) Update CHANGELOG.md
• [ ] (If possible) Add tests

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 20.25%. Comparing base (41936c1) to head (0b804c7). Report is 1 commits behind head on develop.

Files	Patch %	Lines
packages/frontend/src/pages/admin/users.vue	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #14406 +/- ## ============================================ - Coverage 39.91% 20.25% -19.67% ============================================ Files 1545 723 -822 Lines 190505 100283 -90222 Branches 2654 1049 -1605 ============================================ - Hits 76046 20308 -55738 + Misses 113898 79434 -34464 + Partials 561 541 -20 ```

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[syuilo]

🙏🏻