Add support for const sweep with None #15680

Job	Run time
Changed files test	1m 6s
Build protos	8s
Doc test	1m 56s
Coverage check	9m 58s
Format check	7s
Isolated pytest Ubuntu	6m 42s
Lint check	2m 45s
Pytest MacOS (3.10)	6m 25s
Type check	1m 18s
Pytest MacOS (3.11)	6m 3s
Notebook formatting	14s
Notebook Tests against PR	10m 8s
Pytest MacOS (3.12)	9m 27s
Changed Notebooks Isolated Test against Cirq stable (partition-0)	53s
Changed Notebooks Isolated Test against Cirq stable (partition-1)	53s
Packaging test	1m 5s
Pytest Ubuntu (3.10)	6m 12s
Changed Notebooks Isolated Test against Cirq stable (partition-2)	1m 4s
Pytest Ubuntu (3.11)	4m 57s
Check consistency of requirements	19s
Changed Notebooks Isolated Test against Cirq stable (partition-3)	44s
Pytest Ubuntu (3.12)	5m 16s
Shell check	6s
Bundle file consistency	44s
Typescript tests coverage	32s
Typescript tests	37s
Typescript lint check	31s
Pytest Windows (3.10)	13m 45s
Misc check	6s
Pytest Windows (3.11)	12m 12s
Pytest Windows (3.12)	14m 8s
	2h 0m 21s

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