Finish migration from int64 durations to durationpb (#7147)

This is a cleanup PR finishing the migration from int64 durations to
protobuf `*durationpb.Duration` by removing all usage of the old int64
fields. In the previous PR
https://github.com/letsencrypt/boulder/pull/7146 all fields were
switched to read from the protobuf durationpb fields.

Fixes https://github.com/letsencrypt/boulder/issues/7097

ra/ra.go

@@ -1496,9 +1496,8 @@ func (ra *RegistrationAuthorityImpl) checkCertificatesPerFQDNSetLimit(ctx contex
 	}
 
 	prevIssuances, err := ra.SA.FQDNSetTimestampsForWindow(ctx, &sapb.CountFQDNSetsRequest{
-		Domains:  names,
-		WindowNS: limit.Window.Duration.Nanoseconds(),
-		Window:   durationpb.New(limit.Window.Duration),
+		Domains: names,
+		Window:  durationpb.New(limit.Window.Duration),
 	})
 	if err != nil {
 		return fmt.Errorf("checking duplicate certificate limit for %q: %s", names, err)

sa/proto/sa.proto

@@ -191,7 +191,7 @@ message CountOrdersRequest {
 
 message CountFQDNSetsRequest {
   // Next unused field number: 4
-  int64 windowNS = 1;
+  reserved 1; // Previously windowNS
   repeated string domains = 2;
   google.protobuf.Duration window = 3;
 }

sa/sa_test.go

@@ -876,20 +876,17 @@ func TestFQDNSets(t *testing.T) {
 
 	// Invalid Window
 	req := &sapb.CountFQDNSetsRequest{
-		Domains:  names,
-		WindowNS: 0,
-		Window:   nil,
+		Domains: names,
+		Window:  nil,
 	}
 	_, err = sa.CountFQDNSets(ctx, req)
 	test.AssertErrorIs(t, err, errIncompleteRequest)
 
 	threeHours := time.Hour * 3
 	req = &sapb.CountFQDNSetsRequest{
-		Domains:  names,
-		WindowNS: threeHours.Nanoseconds(),
-		Window:   durationpb.New(threeHours),
+		Domains: names,
+		Window:  durationpb.New(threeHours),
 	}
-	test.AssertEquals(t, time.Duration(req.WindowNS), req.Window.AsDuration())
 	// only one valid
 	count, err := sa.CountFQDNSets(ctx, req)
 	test.AssertNotError(t, err, "Failed to count name sets")
@@ -945,20 +942,17 @@ func TestFQDNSetTimestampsForWindow(t *testing.T) {
 
 	// Invalid Window
 	req := &sapb.CountFQDNSetsRequest{
-		Domains:  names,
-		WindowNS: 0,
-		Window:   nil,
+		Domains: names,
+		Window:  nil,
 	}
 	_, err = sa.FQDNSetTimestampsForWindow(ctx, req)
 	test.AssertErrorIs(t, err, errIncompleteRequest)
 
 	window := time.Hour * 3
 	req = &sapb.CountFQDNSetsRequest{
-		Domains:  names,
-		WindowNS: window.Nanoseconds(),
-		Window:   durationpb.New(window),
+		Domains: names,
+		Window:  durationpb.New(window),
 	}
-	test.AssertEquals(t, time.Duration(req.WindowNS), req.Window.AsDuration())
 
 	// Ensure zero issuance has occurred for names.
 	resp, err := sa.FQDNSetTimestampsForWindow(ctx, req)