enhance(backend): refine system account (#15530)

* wip

* wip

* wip

* Update SystemAccountService.ts

* Update 1740121393164-system-accounts.js

* Update DeleteAccountService.ts

* wip

* wip

* wip

* wip

* Update 1740121393164-system-accounts.js

* Update RepositoryModule.ts

* wip

* wip

* wip

* Update ApRendererService.ts

* wip

* wip

* Update SystemAccountService.ts

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* add print logs

* ログが長すぎて出てないかもしれない

* fix migration

* refactor

* fix fed-tests

* Update RelayService.ts

* merge

* Update user.test.ts

* chore: emit log

* fix: tweak sleep duration

* fix: exit 1

* fix: wait for misskey processes to become healthy

* fix: longer sleep for user deletion

* fix: make sleep longer again

* デッドロック解消の試み

https://github.com/misskey-dev/misskey/issues/15005

* Revert "デッドロック解消の試み"

This reverts commit 266141f66f.

* wip

* Update SystemAccountService.ts

---------

Co-authored-by: おさむのひと <46447427+samunohito@users.noreply.github.com>
Co-authored-by: zyoshoka <107108195+zyoshoka@users.noreply.github.com>

packages/backend/test-federation/test/abuse-report.test.ts

@@ -35,7 +35,7 @@ describe('Abuse report', () => {
 			const reportsInB = await bModerator.client.request('admin/abuse-user-reports', {});
 			const reportInB = reportsInB.filter(report => report.comment.includes(comment))[0];
 			// NOTE: reporter is not Alice, and is not moderator in A
-			strictEqual(reportInB.reporter.url, 'https://a.test/@instance.actor');
+			strictEqual(reportInB.reporter.url, 'https://a.test/@system.actor');
 			strictEqual(reportInB.targetUserId, bob.id);
 
 			// NOTE: cannot forward multiple times