Fix CI: extend grace periods for MSRC feeds and expand test coverage for file validation. (#37991)

1. Root cause: cmd/msrc/generate.go

Problem: The MSRC feed generator panicked when the January 2026 feed
wasn't available. The grace period was only 5 days, but MSRC feed
publication dates vary (not available right now).

  Fix: Extended grace period from 5 to 15 days.

2. Defensive fix:
server/vulnerabilities/macoffice/integration_sync_test.go

Problem: Test only checked for files from the last 2 days, which failed
when the NVD repo hadn't published for a few days.

  Fix: Extended tolerance to 7 days.

cmd/msrc/generate.go

@@ -71,11 +71,11 @@ func main() {
 
 // windowsBulletinGracePeriod returns whether we are within the grace period for a MSRC monthly feed to exist.
 //
-// E.g. September 2024 bulletin was released on the 2nd, thus we add some grace period (5 days)
-// for Microsoft to publish the current month bulletin.
+// MSRC monthly feeds are typically published early in the month, but the exact date varies.
+// We use a 15-day grace period to account for this variability.
 func windowsBulletinGracePeriod(month time.Month, year int) bool {
 	now := time.Now()
-	return month == now.Month() && year == now.Year() && now.Day() <= 5
+	return month == now.Month() && year == now.Year() && now.Day() <= 15
 }
 
 func update(

server/vulnerabilities/macoffice/integration_sync_test.go

@@ -3,6 +3,7 @@ package macoffice
 import (
 	"context"
 	"os"
+	"slices"
 	"testing"
 	"time"
 
@@ -28,21 +29,19 @@ func TestIntegrationsSync(t *testing.T) {
 
 	require.NoError(t, err)
 
-	// Checking for the presence of the file for today or yesterday
-	// in case the NVD repo is having delays publishing the data
-	todayFilename := io.MacOfficeRelNotesFileName(time.Now())
-	yesterdayFilename := io.MacOfficeRelNotesFileName(time.Now().AddDate(0, 0, -1))
+	// Checking for the presence of the file from the last 7 days
+	// in case the NVD repo is having delays publishing the data (weekends, holidays, infra issues, etc.)
+	var expectedFilenames []string
+	for i := range 7 {
+		expectedFilenames = append(expectedFilenames, io.MacOfficeRelNotesFileName(time.Now().AddDate(0, 0, -i)))
+	}
 
 	require.Condition(t, func() bool {
-		return contains(filesInVulnPath, todayFilename) || contains(filesInVulnPath, yesterdayFilename)
-	}, "Expected to find %s or %s in %s", todayFilename, yesterdayFilename, vulnPath)
-}
-
-func contains(slice []string, str string) bool {
-	for _, v := range slice {
-		if v == str {
-			return true
+		for _, expectedFilename := range expectedFilenames {
+			if slices.Contains(filesInVulnPath, expectedFilename) {
+				return true
+			}
 		}
-	}
-	return false
+		return false
+	}, "Expected to find one of %v in %s", expectedFilenames, vulnPath)
 }