Set backupSchedule as required in MongoDB Flex instance (#96)

* Set backupSchedule as required in MongoDB Flex instance

* Update example and generate docs

* Add regex explanation comment

* Fix acceptance test

* Fix map fields

stackit/internal/services/mongodbflex/instance/resource_test.go

@@ -748,3 +748,75 @@ func TestLoadFlavorId(t *testing.T) {
 		})
 	}
 }
+
+func TestSimplifyBackupSchedule(t *testing.T) {
+	tests := []struct {
+		description string
+		input       string
+		expected    string
+	}{
+		{
+			"simple schedule",
+			"0 0 * * *",
+			"0 0 * * *",
+		},
+		{
+			"schedule with leading zeros",
+			"00 00 * * *",
+			"0 0 * * *",
+		},
+		{
+			"schedule with leading zeros 2",
+			"00 001 * * *",
+			"0 1 * * *",
+		},
+		{
+			"schedule with leading zeros 3",
+			"00 0010 * * *",
+			"0 10 * * *",
+		},
+		{
+			"simple schedule with slash",
+			"0 0/6 * * *",
+			"0 0/6 * * *",
+		},
+		{
+			"schedule with leading zeros and slash",
+			"00 00/6 * * *",
+			"0 0/6 * * *",
+		},
+		{
+			"schedule with leading zeros and slash 2",
+			"00 001/06 * * *",
+			"0 1/6 * * *",
+		},
+		{
+			"simple schedule with comma",
+			"0 10,15 * * *",
+			"0 10,15 * * *",
+		},
+		{
+			"schedule with leading zeros and comma",
+			"0 010,0015 * * *",
+			"0 10,15 * * *",
+		},
+		{
+			"simple schedule with comma and slash",
+			"0 0-11/10 * * *",
+			"0 0-11/10 * * *",
+		},
+		{
+			"schedule with leading zeros, comma, and slash",
+			"00 000-011/010 * * *",
+			"0 0-11/10 * * *",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.description, func(t *testing.T) {
+			output := simplifyBackupSchedule(tt.input)
+			if output != tt.expected {
+				t.Fatalf("Data does not match: %s", output)
+			}
+		})
+	}
+}