chore: replace []byte with string and use go:embed for templates

Optimize code a bit.

Signed-off-by: Dmitriy Matrenichev <dmitry.matrenichev@siderolabs.com>

Author: DmitriyMV

internal/app/machined/pkg/controllers/k8s/manifest.go

@@ -112,7 +112,7 @@ func (ctrl *ManifestController) Run(ctx context.Context, r controller.Runtime, l
 				func(r *k8s.Manifest) error {
 					return k8sadapter.Manifest(r).SetYAML(renderedManifest.data)
 				}); err != nil {
-				return fmt.Errorf("error updating manifests: %w", err)
+				return fmt.Errorf("error updating manifest %q: %w", renderedManifest.name, err)
 			}
 		}
 
@@ -122,7 +122,7 @@ func (ctrl *ManifestController) Run(ctx context.Context, r controller.Runtime, l
 			return fmt.Errorf("error listing manifests: %w", err)
 		}
 
-		manifestsToDelete := map[string]struct{}{}
+		manifestsToDelete := make(map[string]struct{}, len(manifests.Items))
 
 		for _, manifest := range manifests.Items {
 			if manifest.Metadata().Owner() != ctrl.Name() {
@@ -192,7 +192,7 @@ func (ctrl *ManifestController) render(cfg k8s.BootstrapManifestsConfigSpec, scr
 
 	type manifestDesc struct {
 		name     string
-		template []byte
+		template string
 	}
 
 	defaultManifests := []manifestDesc{
@@ -252,7 +252,7 @@ func (ctrl *ManifestController) render(cfg k8s.BootstrapManifestsConfigSpec, scr
 				"join":     strings.Join,
 				"contains": strings.Contains,
 			}).
-			Parse(string(defaultManifests[i].template))
+			Parse(defaultManifests[i].template)
 		if err != nil {
 			return nil, fmt.Errorf("error parsing manifest template %q: %w", defaultManifests[i].name, err)
 		}

internal/app/machined/pkg/controllers/k8s/render_secrets_static_pod.go

@@ -158,7 +158,7 @@ func (ctrl *RenderSecretsStaticPodController) Run(ctx context.Context, r control
 
 		type template struct {
 			filename string
-			template []byte
+			template string
 		}
 
 		for _, pod := range []struct {
@@ -253,7 +253,7 @@ func (ctrl *RenderSecretsStaticPodController) Run(ctx context.Context, r control
 				templates: []template{
 					{
 						filename: "kubeconfig",
-						template: []byte("{{ .Secrets.ControllerManagerKubeconfig }}"),
+						template: "{{ .Secrets.ControllerManagerKubeconfig }}",
 					},
 				},
 			},
@@ -265,7 +265,7 @@ func (ctrl *RenderSecretsStaticPodController) Run(ctx context.Context, r control
 				templates: []template{
 					{
 						filename: "kubeconfig",
-						template: []byte("{{ .Secrets.SchedulerKubeconfig }}"),
+						template: "{{ .Secrets.SchedulerKubeconfig }}",
 					},
 				},
 			},
@@ -311,7 +311,7 @@ func (ctrl *RenderSecretsStaticPodController) Run(ctx context.Context, r control
 			for _, templ := range pod.templates {
 				var t *stdlibtemplate.Template
 
-				t, err = stdlibtemplate.New(templ.filename).Parse(string(templ.template))
+				t, err = stdlibtemplate.New(templ.filename).Parse(templ.template)
 				if err != nil {
 					return fmt.Errorf("error parsing template %q: %w", templ.filename, err)
 				}