Set EAP billing event to one-year period

This is consistent with how we treat RESTORE billing events as well- in
general, fees are considered to be amortized over the course of a year (by the
invoicing team).

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=199684843

javatests/google/registry/flows/domain/DomainCreateFlowTest.java

@@ -267,6 +267,7 @@ public class DomainCreateFlowTest extends ResourceFlowTestCase<DomainCreateFlow,
               .setReason(Reason.FEE_EARLY_ACCESS)
               .setTargetId(getUniqueIdFromCommand())
               .setClientId("TheRegistrar")
+              .setPeriodYears(1)
               .setCost(eapFee)
               .setEventTime(clock.nowUtc())
               .setBillingTime(billingTime)