Fix some points that golangci-lint point out.

Author: utam0k

pkg/dazzle/combiner.go

@@ -312,12 +312,8 @@ func mergeEnv(base *ociv1.Image, others []*ociv1.Image, vars []EnvVarCombination
 					envs[k] += ":" + v
 				case EnvVarCombineMergeUnique:
 					var vs []string
-					for _, s := range strings.Split(envValue, ":") {
-						vs = append(vs, s)
-					}
-					for _, s := range strings.Split(v, ":") {
-						vs = append(vs, s)
-					}
+					vs = append(vs, strings.Split(envValue, ":")...)
+					vs = append(vs, strings.Split(v, ":")...)
 
 					vss := []string{}
 					flags := make(map[string]bool)

pkg/dazzle/combiner_test.go

@@ -27,8 +27,6 @@ import (
 )
 
 func TestMergeEnv(t *testing.T) {
-	type args struct {
-	}
 	tests := []struct {
 		name   string
 		base   *ociv1.Image