#806 Standardize JumperClient to use singleton pattern

23+ locations bypass singleton pattern with direct JumperClient() calls. Need to replace with get_jumper_client() in: approvals.py, schedules.py, gateway.py, event_gateway_service.py, cron_recovery_service.py, platform_bootstrap_service.py, storage_service.py, update_service.py, durable_cron.py, scriptplan.py, cron_jobs.py, sleeping_task_scanner.py