Fix htpasswd issues (#1786)

## Description

This fixes issues with generating an htpasswd for external registries
(when it is not needed).

## Related Issue

Fixes #1781 

## Type of change

- [X] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Other (security config, docs update, etc)

## Checklist before merging

- [x] Test, docs, adr added or updated as needed
- [x] [Contributor Guide
Steps](https://github.com/defenseunicorns/zarf/blob/main/CONTRIBUTING.md#developer-workflow)
followed

src/internal/packager/template/template.go

@@ -36,17 +36,20 @@ func Generate(cfg *types.PackagerConfig) (*Values, error) {
 
 	regInfo := cfg.State.RegistryInfo
 
-	pushUser, err := utils.GetHtpasswdString(regInfo.PushUsername, regInfo.PushPassword)
-	if err != nil {
-		return nil, fmt.Errorf("error generating htpasswd string: %w", err)
-	}
+	// Only calculate this for internal registries to allow longer external passwords
+	if regInfo.InternalRegistry {
+		pushUser, err := utils.GetHtpasswdString(regInfo.PushUsername, regInfo.PushPassword)
+		if err != nil {
+			return nil, fmt.Errorf("error generating htpasswd string: %w", err)
+		}
 
-	pullUser, err := utils.GetHtpasswdString(regInfo.PullUsername, regInfo.PullPassword)
-	if err != nil {
-		return nil, fmt.Errorf("error generating htpasswd string: %w", err)
-	}
+		pullUser, err := utils.GetHtpasswdString(regInfo.PullUsername, regInfo.PullPassword)
+		if err != nil {
+			return nil, fmt.Errorf("error generating htpasswd string: %w", err)
+		}
 
-	generated.htpasswd = fmt.Sprintf("%s\\n%s", pushUser, pullUser)
+		generated.htpasswd = fmt.Sprintf("%s\\n%s", pushUser, pullUser)
+	}
 
 	generated.registry = regInfo.Address