ra, wfe: use TimestampsForWindow to check renewal #7469

Job	Run time
vendorcheck (1.22.5)	26s
vendorcheck (1.22.5)	26s
b (go1.23.1_2024-09-05, ./t.sh --lints --generate)	3m 22s
b (go1.23.1_2024-09-05, ./t.sh --lints --generate)	3m 22s
govulncheck	10s
govulncheck	10s
b (go1.23.1_2024-09-05, ./t.sh --integration)	5m 57s
b (go1.23.1_2024-09-05, ./t.sh --integration)	5m 40s
b (go1.23.1_2024-09-05, ./tn.sh --integration)	4m 18s
b (go1.23.1_2024-09-05, ./tn.sh --integration)	4m 12s
b (go1.23.1_2024-09-05, ./t.sh --unit --enable-race-detection)	7m 41s
b (go1.23.1_2024-09-05, ./t.sh --unit --enable-race-detection)	7m 41s
b (go1.23.1_2024-09-05, ./tn.sh --unit --enable-race-detection)	7m 51s
b (go1.23.1_2024-09-05, ./tn.sh --unit --enable-race-detection)	7m 51s
b (go1.23.1_2024-09-05, ./t.sh --start-py)	2m 43s
b (go1.23.1_2024-09-05, ./t.sh --start-py)	2m 43s
Boulder CI Test Matrix	1s
Boulder CI Test Matrix	1s
	1h 4m 35s

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