remove `ENABLE_BLS_OPS_OUTSIDE_GUARD` #1896

Job	Run time
Wheel on macos-12 py-3.8	3m 15s
Wheel on ubuntu-latest py-3.8	2m 42s
Wheel on windows-latest py-3.8	2m 54s
Checks	1m 9s
coverage	8m 13s
Run fuzz targets (macos-12, 3.8)	16m 49s
Run fuzz targets (ubuntu-latest, 3.8)	12m 59s
Unit tests (macos-12, 3.8)	10m 19s
Unit tests (ubuntu-latest, 3.8)	3m 50s
Unit tests (windows-latest, 3.8)	6m 53s
Upload to PyPI	28s
	1h 9m 31s

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