Remove deprecated qubits in contrib graphdevice.

[MichaelBroughton]

No description provided.

[pavoljuhas]

Perhaps this one needs to be replaces with device.qubits ?

Cirq/docs/tutorials/google/identifying_hardware_changes.ipynb

Lines 286 to 290 in 640ef8f

	"\n",
	"# Get qubit set\n",
	"qubits = device.qubit_set()\n",
	"\n",
	"# Limit device qubits to only those before row/column `device_limit`\n",

[pavoljuhas]

Please check this qubit_set() use in a notebook -

Cirq/docs/tutorials/google/identifying_hardware_changes.ipynb

Lines 286 to 290 in 640ef8f

	"\n",
	"# Get qubit set\n",
	"qubits = device.qubit_set()\n",
	"\n",
	"# Limit device qubits to only those before row/column `device_limit`\n",

[MichaelBroughton]

Ahhhh that's a good catch Pavol! When I went back to try and fix that tutorial I ran into a lot of problems, after fixing the use of XmonDevice and qubit_set I also saw that none of our QCS devices are calibrated with ISWAP anymore and even worse none of them are reporting two qubit metrics we can use for XEB. Perhaps we should merge this now and open an issue to fix up this tutorial seperately (it is currently in a pretty broken state). WDYT ?

[pavoljuhas]

Sure, sounds good. I was hoping it would be a one-word change, but if it is a bigger beast it should have its own PR.

[pavoljuhas]

LGTM