Restrict domain transfer pricing to 1 year

This CL restricts domain transfer pricing lookups (on domain check and info) to
only support a 1-year period for inquiring about transfer fees.  That treatment
matches what we do for domain restores, which are also always one year.  This is
a followup to [] which disallowed actual transfer request flows from
specifying multi-year periods.

Since it's no longer necessary, this CL also changes the domain transfer pricing
logic to drop the years parameter, including removing the parameter from the
custom pricing logic TransferPriceParameters object.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=150367839

java/google/registry/flows/domain/DomainCheckFlow.java

@@ -90,6 +90,7 @@ import org.joda.time.DateTime;
  * @error {@link DomainFlowUtils.RestoresAreAlwaysForOneYearException}
  * @error {@link DomainFlowUtils.TldDoesNotExistException}
  * @error {@link DomainFlowUtils.TrailingDashException}
+ * @error {@link DomainFlowUtils.TransfersAreAlwaysForOneYearException}
  * @error {@link DomainFlowUtils.UnknownFeeCommandException}
  * @error {@link OnlyCheckedNamesCanBeFeeCheckedException}
  */