chore: remove unused parameter from util funcs; add unit test

Added the unit tests from
https://github.com/kubernetes/kubernetes/blob/master/pkg/util/slice/slice_test.go
(minus modifier tests) so we can be sure to not change behaviour.

pkg/utils/util_test.go

@@ -25,6 +25,58 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
+func TestContainsString(t *testing.T) {
+	src := []string{"aa", "bb", "cc"}
+	if !ContainsString(src, "bb") {
+		t.Errorf("ContainsString didn't find the string as expected")
+	}
+}
+
+func TestRemoveString(t *testing.T) {
+	tests := []struct {
+		testName string
+		input    []string
+		remove   string
+		want     []string
+	}{
+		{
+			testName: "Nil input slice",
+			input:    nil,
+			remove:   "",
+			want:     nil,
+		},
+		{
+			testName: "Slice doesn't contain the string",
+			input:    []string{"a", "ab", "cdef"},
+			remove:   "NotPresentInSlice",
+			want:     []string{"a", "ab", "cdef"},
+		},
+		{
+			testName: "All strings removed, result is nil",
+			input:    []string{"a"},
+			remove:   "a",
+			want:     nil,
+		},
+		{
+			testName: "One string removed",
+			input:    []string{"a", "ab", "cdef"},
+			remove:   "ab",
+			want:     []string{"a", "cdef"},
+		},
+		{
+			testName: "All(three) strings removed",
+			input:    []string{"ab", "a", "ab", "cdef", "ab"},
+			remove:   "ab",
+			want:     []string{"a", "cdef"},
+		},
+	}
+	for _, tt := range tests {
+		if got := RemoveString(tt.input, tt.remove); !reflect.DeepEqual(got, tt.want) {
+			t.Errorf("%v: RemoveString(%v, %q) = %v WANT %v", tt.testName, tt.input, tt.remove, got, tt.want)
+		}
+	}
+}
+
 func TestGetSecretReference(t *testing.T) {
 	testcases := map[string]struct {
 		secretParams    secretParamsMap