fix irrevocable leases API deadlock on m.coreStateLock (#11815)
fix irrevocable leases API deadlock on m.coreStateLock (#11815)

* fix m.coreStateLock deadlock for API handler code

* improve lock comment
rnaveiras/vault,rnaveiras/vault,hashicorp/vault,rnaveiras/vault,rnaveiras/vault,hashicorp/vault,hashicorp/vault,hashicorp/vault,hashicorp/vault,rnaveiras/vault,hashicorp/vault