Rename 'now' to 'validUntil' in GetAuthz requests (#7631)

The name "now" was always misleading, because we never set the value to
be the actual current time, we always set it to be some time in the
future to avoid returning authzs which expire in the very near future.
Changing the name to "validUntil" matches the current naming in
GetPendingAuthorizationRequest.

mocks/sa.go

@@ -468,10 +468,10 @@ func (sa *StorageAuthorityReadOnly) GetValidAuthorizations2(ctx context.Context,
 	if req.RegistrationID != 1 && req.RegistrationID != 5 && req.RegistrationID != 4 {
 		return &sapb.Authorizations{}, nil
 	}
-	now := req.Now.AsTime()
+	expiryCutoff := req.ValidUntil.AsTime()
 	auths := &sapb.Authorizations{}
 	for _, name := range req.Domains {
-		exp := now.AddDate(100, 0, 0)
+		exp := expiryCutoff.AddDate(100, 0, 0)
 		authzPB, err := bgrpc.AuthzToPB(core.Authorization{
 			Status:         core.StatusValid,
 			RegistrationID: req.RegistrationID,
@@ -485,7 +485,7 @@ func (sa *StorageAuthorityReadOnly) GetValidAuthorizations2(ctx context.Context,
 					Status:    core.StatusValid,
 					Type:      core.ChallengeTypeDNS01,
 					Token:     "exampleToken",
-					Validated: &now,
+					Validated: &expiryCutoff,
 				},
 			},
 		})

ra/ra.go

@@ -2100,7 +2100,7 @@ func (ra *RegistrationAuthorityImpl) RevokeCertByApplicant(ctx context.Context,
 		authzMapPB, err = ra.SA.GetValidAuthorizations2(ctx, &sapb.GetValidAuthorizationsRequest{
 			RegistrationID: req.RegID,
 			Domains:        cert.DNSNames,
-			Now:            timestamppb.New(ra.clk.Now()),
+			ValidUntil:     timestamppb.New(ra.clk.Now()),
 		})
 		if err != nil {
 			return nil, err
@@ -2528,7 +2528,7 @@ func (ra *RegistrationAuthorityImpl) NewOrder(ctx context.Context, req *rapb.New
 
 	getAuthReq := &sapb.GetAuthorizationsRequest{
 		RegistrationID: newOrder.RegistrationID,
-		Now:            timestamppb.New(authzExpiryCutoff),
+		ValidUntil:     timestamppb.New(authzExpiryCutoff),
 		Domains:        newOrder.Names,
 	}
 	existingAuthz, err := ra.SA.GetAuthorizations2(ctx, getAuthReq)