ratelimits: Fetch correct limit when building transaction #5736

Job	Run time
govulncheck (1.21.5)	56s
b (go1.21.5_2024-02-14, ./t.sh --lints --generate)	2m 12s
vendorcheck (1.21.5)	12s
b (go1.21.5_2024-02-14, ./t.sh --integration && ./test/test-caa-log-checker.sh)	4m 26s
b (go1.21.5_2024-02-14, ./tn.sh --integration)	6m 33s
b (go1.21.5_2024-02-14, ./t.sh --unit --enable-race-detection)	5m 39s
b (go1.21.5_2024-02-14, ./tn.sh --unit --enable-race-detection)	5m 38s
b (go1.21.5_2024-02-14, ./t.sh --start-py)	1m 47s
b (go1.22.0_2024-02-14, ./t.sh --lints --generate)	42s
b (go1.22.0_2024-02-14, ./t.sh --integration && ./test/test-caa-log-checker.sh)	4m 14s
b (go1.22.0_2024-02-14, ./tn.sh --integration)	6m 30s
b (go1.22.0_2024-02-14, ./t.sh --unit --enable-race-detection)	5m 46s
b (go1.22.0_2024-02-14, ./tn.sh --unit --enable-race-detection)	5m 42s
b (go1.22.0_2024-02-14, ./t.sh --start-py)	1m 26s
Boulder CI Test Matrix	1s
	51m 44s

Provide feedback