pdx_benchmarks: Let the service create sockets by itself

Default implementation of Endpoint::Create() takes the socket name
as provided by the init process when it forks. pdx_benchmark is not
a service but a command-line utility and it is being started manually
and not through init process. So, named sockets are not available.
Instead, it must create a socket by the specified name. For this,
it must use Endpoint::CreateAndBindSocket() method.

Bug: 37507039
Test: Tested manually on device: `pdx_benchmarks --service foo`.
Change-Id: If30bfa7138f5a97ba0bff9e61460c6bd3697ec19