Update TestServer error string (#12954)
Update TestServer error string (#12954)

Update the error string expected from parsing unknown units in a
duration.
rnaveiras/vault,rnaveiras/vault,hashicorp/vault,hashicorp/vault,hashicorp/vault,hashicorp/vault,rnaveiras/vault,rnaveiras/vault,hashicorp/vault,hashicorp/vault,rnaveiras/vault