Add EPLG to backend configuration

[conradhaupt]

What is the expected feature or enhancement?

Currently backend.configuration() will return the measured quantum volume and CLOPS for a device, if it exists on quantum-computing.ibm.com. The new 127 and 133 qubits devices also report the newer EPLG metri, but this is not currently reported in backend.configuration(). This enhancement would be to include EPLG in backend.configuration() for, at least, the new >100 qubits devices; where it is available.

Acceptance criteria

The following code, or equivalent, should return the EPLG value displayed on https://quantum-computing.ibm.com:

service = QiskitRuntimeService()
backend = service.get_backend("ibm_sherbrooke")

eplg = backend.configuration().eplg
print("EPLG for {} is {}".format(backend.name, eplg)

[jyu00]

This would need to be added to the configuration file provided by the backend (server side)