distro/rhel: don't print warnings in checkOptions()

When collecting warnings in checkOptions() functions, don't
`log.Print()` the warning.  Let the caller decide whether to print them,
suppress them, make them errors, format them, etc.

pkg/distro/rhel/rhel10/options.go

@@ -2,7 +2,6 @@ package rhel10
 
 import (
 	"fmt"
-	"log"
 
 	"slices"
 
@@ -76,9 +75,7 @@ func checkOptions(t *rhel.ImageType, bp *blueprint.Blueprint, options distro.Ima
 	}
 
 	if customizations.GetFIPS() && !common.IsBuildHostFIPSEnabled() {
-		w := fmt.Sprintln(common.FIPSEnabledImageWarning)
-		log.Print(w)
-		warnings = append(warnings, w)
+		warnings = append(warnings, fmt.Sprintln(common.FIPSEnabledImageWarning))
 	}
 
 	instCust, err := customizations.GetInstaller()

pkg/distro/rhel/rhel8/options.go

@@ -2,7 +2,6 @@ package rhel8
 
 import (
 	"fmt"
-	"log"
 	"strings"
 
 	"slices"
@@ -91,14 +90,10 @@ func checkOptions(t *rhel.ImageType, bp *blueprint.Blueprint, options distro.Ima
 	// TODO(edge): directly error if these options are provided when rhel-9.5's time arrives
 	if t.Name() == "edge-commit" || t.Name() == "edge-container" {
 		if customizations.GetUsers() != nil {
-			w := fmt.Sprintf("Please note that user customizations on %q image type are deprecated and will be removed in the near future\n", t.Name())
-			log.Print(w)
-			warnings = append(warnings, w)
+			warnings = append(warnings, fmt.Sprintf("Please note that user customizations on %q image type are deprecated and will be removed in the near future\n", t.Name()))
 		}
 		if customizations.GetGroups() != nil {
-			w := fmt.Sprintf("Please note that group customizations on %q image type are deprecated and will be removed in the near future\n", t.Name())
-			log.Print(w)
-			warnings = append(warnings, w)
+			warnings = append(warnings, fmt.Sprintf("Please note that group customizations on %q image type are deprecated and will be removed in the near future\n", t.Name()))
 		}
 	}
 
@@ -171,7 +166,6 @@ func checkOptions(t *rhel.ImageType, bp *blueprint.Blueprint, options distro.Ima
 
 	if customizations.GetFIPS() && !common.IsBuildHostFIPSEnabled() {
 		w := fmt.Sprintln(common.FIPSEnabledImageWarning)
-		log.Print(w)
 		warnings = append(warnings, w)
 	}
 

pkg/distro/rhel/rhel9/options.go

@@ -2,7 +2,6 @@ package rhel9
 
 import (
 	"fmt"
-	"log"
 	"strings"
 
 	"slices"
@@ -104,14 +103,10 @@ func checkOptions(t *rhel.ImageType, bp *blueprint.Blueprint, options distro.Ima
 	// TODO(edge): directly error if these options are provided when rhel-9.5's time arrives
 	if t.Name() == "edge-commit" || t.Name() == "edge-container" {
 		if customizations.GetUsers() != nil {
-			w := fmt.Sprintf("Please note that user customizations on %q image type are deprecated and will be removed in the near future\n", t.Name())
-			log.Print(w)
-			warnings = append(warnings, w)
+			warnings = append(warnings, fmt.Sprintf("Please note that user customizations on %q image type are deprecated and will be removed in the near future\n", t.Name()))
 		}
 		if customizations.GetGroups() != nil {
-			w := fmt.Sprintf("Please note that group customizations on %q image type are deprecated and will be removed in the near future\n", t.Name())
-			log.Print(w)
-			warnings = append(warnings, w)
+			warnings = append(warnings, fmt.Sprintf("Please note that group customizations on %q image type are deprecated and will be removed in the near future\n", t.Name()))
 		}
 	}
 
@@ -189,9 +184,7 @@ func checkOptions(t *rhel.ImageType, bp *blueprint.Blueprint, options distro.Ima
 	}
 
 	if customizations.GetFIPS() && !common.IsBuildHostFIPSEnabled() {
-		w := fmt.Sprintln(common.FIPSEnabledImageWarning)
-		log.Print(w)
-		warnings = append(warnings, w)
+		warnings = append(warnings, fmt.Sprintln(common.FIPSEnabledImageWarning))
 	}
 
 	instCust, err := customizations.GetInstaller()