Add num_qubits to DepolarizingChannel cirq_google serialization #19077

Job	Run time
Format check	12s
Type check	1m 52s
Packaging test	1m 9s
Misc check	8s
Changed files test	1m 7s
Lint check	2m 17s
Shell check	7s
Build protos	17s
Pytest Windows (3.11)	8m 12s
Pytest Windows (3.12)	11m 5s
Pytest Windows (3.13)	8m 54s
Notebook Tests against PR	9m 18s
Changed Notebooks Isolated Test against Cirq stable (partition-1)	46s
Changed Notebooks Isolated Test against Cirq stable (partition-2)	50s
Changed Notebooks Isolated Test against Cirq stable (partition-0)	48s
Typescript tests coverage	38s
Changed Notebooks Isolated Test against Cirq stable (partition-3)	47s
Isolated pytest Ubuntu	8m 1s
Coverage check	13m 39s
Pytest MacOS (3.13)	10m 54s
Pytest MacOS (3.12)	6m 51s
Pytest MacOS (3.11)	6m 0s
Bundle file consistency	48s
Typescript lint check	35s
Check consistency of requirements	20s
Notebook formatting	12s
Doc test	1m 31s
Pytest Ubuntu (3.11)	6m 15s
Pytest Ubuntu (3.12)	7m 26s
Typescript tests	40s
Pytest Ubuntu (3.13)	6m 53s
	1h 58m 32s

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