MAINT: Simplify file identifiers generation #4119

Job	Run time
Check code style issues	25s
Build & verify package	15s
pytest on windows	4m 49s
pytest on 3.7 (crypto-lib: cryptography)	3m 30s
pytest on 3.8 (crypto-lib: cryptography)	3m 51s
pytest on 3.9 (crypto-lib: cryptography)	3m 57s
pytest on 3.10 (crypto-lib: cryptography)	3m 36s
pytest on 3.11 (crypto-lib: cryptography)	3m 20s
pytest on 3.12 (crypto-lib: cryptography)	4m 54s
pytest on 3.6 (crypto-lib: pycryptodome)	3m 43s
pytest on 3.7 (crypto-lib: none)	4m 3s
Combine & check coverage.	11s
	36m 34s

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