Proposal: NONE to NO_CACHE

[cicdw]

We've seen multiple get users get confused about the NONE cache policy, thinking that passing the Python None is sufficient to engage this policy. To avoid this confusion, this PR proposes renaming NONE to NO_CACHE to be explicit, updates docs accordingly, and keeps NONE around to avoid any breaking changes.

cc: @gabcoyne

[codspeed-hq]

CodSpeed Performance Report

Merging #16650 will improve performances by 14.44%

_{Comparing none-to-no-cache (34a0082) with main (ada6eee)}

Summary

⚡ 1 improvements
✅ 2 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	none-to-no-cache	Change
⚡	bench_flow_decorator	5.3 ms	4.6 ms	+14.44%

[desertaxle]

Makes sense to me!