SA: Improve concurrency robustness of CRL leasing transactions #8049

Job	Run time
govulncheck	15s
vendorcheck (1.22.5)	26s
b (go1.23.6_2025-02-11, ./t.sh --lints --generate)	3m 20s
b (go1.23.6_2025-02-11, ./t.sh --integration)	5m 31s
b (go1.23.6_2025-02-11, ./tn.sh --integration)	7m 30s
b (go1.23.6_2025-02-11, ./t.sh --unit --enable-race-detection)	7m 45s
b (go1.23.6_2025-02-11, ./tn.sh --unit --enable-race-detection)	7m 55s
b (go1.23.6_2025-02-11, ./t.sh --start-py)	2m 50s
b (go1.24.0_2025-02-11, ./t.sh --lints --generate)	3m 23s
b (go1.24.0_2025-02-11, ./t.sh --integration)	5m 48s
b (go1.24.0_2025-02-11, ./tn.sh --integration)	7m 59s
b (go1.24.0_2025-02-11, ./t.sh --unit --enable-race-detection)	7m 48s
b (go1.24.0_2025-02-11, ./tn.sh --unit --enable-race-detection)	7m 53s
b (go1.24.0_2025-02-11, ./t.sh --start-py)	3m 1s
Boulder CI Test Matrix	1s
	1h 11m 25s

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