gh-114940: Use fine-grained mutex protection for `PyInterpreterState.threads` #131388

Job	Run time
Change detection / Compute changed files	11s
Check if Autoconf files are up to date	20s
Check if generated files are up to date	3m 59s
Windows MSI${{ '' }}	0s
Docs	0s
Address sanitizer (ubuntu-22.04)	9m 1s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.0.15)	2m 41s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.1.7)	2m 13s
Hypothesis tests on Ubuntu	5m 26s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.2.3)	2m 43s
CIFuzz (address)	19m 8s
Ubuntu SSL tests with OpenSSL (ubuntu-22.04, 3.3.2)	2m 35s
CIFuzz (undefined)	21m 3s
CIFuzz (memory)	20m 37s
Thread sanitizer / Thread sanitizer	4m 59s
WASI / build and test	6m 28s
Thread sanitizer (free-threading) / Thread sanitizer	7m 8s
Windows / build (arm64)	2m 54s
Windows (free-threading) / build (arm64)	3m 5s
Windows / build and test (Win32)	16m 6s
Windows (free-threading) / build and test (Win32)	23m 45s
Windows / build and test (x64)	15m 33s
Windows (free-threading) / build and test (x64)	22m 49s
macOS (free-threading) / build and test (ghcr.io/cirruslabs/macos-runner:sonoma)	5m 23s
macOS / build and test (ghcr.io/cirruslabs/macos-runner:sonoma)	4m 29s
macOS / build and test (macos-13)	1m 49s
Ubuntu / build and test (ubuntu-22.04)	1m 44s
Ubuntu (free-threading) / build and test (ubuntu-22.04)	2m 1s
All required checks pass	2s
	3h 28m 12s

Provide feedback