Fix "Unknown task: git_fsck" error on admin dashboard (#11468)

options/locale/locale_en-US.ini

 dashboard.resync_all_hooks = Resynchronize pre-receive, update and post-receive hooks of all repositories.
 dashboard.reinit_missing_repos = Reinitialize all missing Git repositories for which records exist
 dashboard.sync_external_users = Synchronize external user data
-dashboard.git_fsck = Execute health checks on all repositories
 dashboard.server_uptime = Server Uptime
 dashboard.current_goroutine = Current Goroutines
 dashboard.current_memory_usage = Current Memory Usage

templates/admin/dashboard.tmpl

 							<td><button type="submit" class="ui green button" name="op" value="sync_external_users">{{svg "octicon-triangle-right" 16}} {{.i18n.Tr "admin.dashboard.operation_run"}}</button></td>
 						</tr>
 						<tr>
-							<td>{{.i18n.Tr "admin.dashboard.git_fsck"}}</td>
-							<td><button type="submit" class="ui green button" name="op" value="git_fsck">{{svg "octicon-triangle-right" 16}} {{.i18n.Tr "admin.dashboard.operation_run"}}</button></td>
+							<td>{{.i18n.Tr "admin.dashboard.repo_health_check"}}</td>
+							<td><button type="submit" class="ui green button" name="op" value="repo_health_check">{{svg "octicon-triangle-right" 16}} {{.i18n.Tr "admin.dashboard.operation_run"}}</button></td>
 						</tr>
 						<tr>
 							<td>{{.i18n.Tr "admin.dashboard.delete_generated_repository_avatars"}}</td>