lib: migrate to stable `LazyLock` #271

Job	Run time
Build, lint and run unit tests	3m 9s
cassandra-integration-tests (RELEASE-3.X, 8)	21m 55s
Scylla ITs (ENTERPRISE-RELEASE)	16m 19s
Scylla ITs (ENTERPRISE-PRIOR-RELEASE)	18m 30s
Scylla ITs (OSS-RELEASE)	16m 10s
Scylla ITs (OSS-PRIOR-RELEASE)	16m 11s
Scylla ITs (5.4.8)	17m 44s
	1h 49m 58s

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