Zoekt: Fix scheduling service statement timeout

What does this MR do and why?

This MR fixes ActiveRecord::QueryCanceled exception in Search::Zoekt::SchedulingService

The problematic spot was the GitlabSubscription subquery

Query before

SELECT "namespaces"."id", "namespaces"."name", "namespaces"."path", "namespaces"."owner_id", "namespaces"."created_at", "namespaces"."updated_at", "namespaces"."type", "namespaces"."description", "namespaces"."avatar", "namespaces"."membership_lock", "namespaces"."share_with_group_lock", "namespaces"."visibility_level", "namespaces"."request_access_enabled", "namespaces"."ldap_sync_status", "namespaces"."ldap_sync_error", "namespaces"."ldap_sync_last_update_at", "namespaces"."ldap_sync_last_successful_update_at", "namespaces"."ldap_sync_last_sync_at", "namespaces"."lfs_enabled", "namespaces"."description_html", "namespaces"."parent_id", "namespaces"."shared_runners_minutes_limit", "namespaces"."repository_size_limit", "namespaces"."require_two_factor_authentication", "namespaces"."two_factor_grace_period", "namespaces"."cached_markdown_version", "namespaces"."project_creation_level", "namespaces"."runners_token", "namespaces"."file_template_project_id", "namespaces"."saml_discovery_token", "namespaces"."runners_token_encrypted", "namespaces"."custom_project_templates_group_id", "namespaces"."auto_devops_enabled", "namespaces"."extra_shared_runners_minutes_limit", "namespaces"."last_ci_minutes_notification_at", "namespaces"."last_ci_minutes_usage_notification_level", "namespaces"."subgroup_creation_level", "namespaces"."emails_disabled", "namespaces"."max_pages_size", "namespaces"."max_artifacts_size", "namespaces"."mentions_disabled", "namespaces"."default_branch_protection", "namespaces"."max_personal_access_token_lifetime", "namespaces"."push_rule_id", "namespaces"."shared_runners_enabled", "namespaces"."allow_descendants_override_disabled_shared_runners", "namespaces"."traversal_ids", "namespaces"."organization_id" FROM "namespaces" WHERE "namespaces"."type" = 'Group' AND "namespaces"."parent_id" IS NULL AND "namespaces"."id" IN (SELECT "gitlab_subscriptions"."namespace_id" FROM "gitlab_subscriptions" INNER JOIN "plans" ON "plans"."id" = "gitlab_subscriptions"."hosted_plan_id" WHERE ("gitlab_subscriptions"."trial" = FALSE OR "gitlab_subscriptions"."trial" IS NULL) AND "plans"."name" IN ('bronze', 'silver', 'premium', 'gold', 'ultimate', 'ultimate_trial', 'ultimate_trial_paid_customer', 'premium_trial', 'opensource') AND (end_date > '2024-03-19' OR end_date IS NULL)) ORDER BY "namespaces"."id" ASC LIMIT 1000

https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/27020/commands/84034

Query after

SELECT "gitlab_subscriptions"."id" FROM "gitlab_subscriptions" INNER JOIN "plans" ON "plans"."id" = "gitlab_subscriptions"."hosted_plan_id" WHERE ("gitlab_subscriptions"."trial" = FALSE OR "gitlab_subscriptions"."trial" IS NULL) AND "plans"."name" IN ('bronze', 'silver', 'premium', 'gold', 'ultimate', 'ultimate_trial', 'ultimate_trial_paid_customer', 'premium_trial', 'opensource') AND (end_date IS NULL OR end_date >= '2024-03-19') AND "gitlab_subscriptions"."id" >= 1 ORDER BY "gitlab_subscriptions"."id" ASC LIMIT 1 OFFSET 100

https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/27020/commands/84033

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