If I understand correctly, you just want the switch to control whether the LEDs blink or not:

Switch is ON - LEDs are blinking;

Switch is OFF - LEDs stay off.

IS that right?
If so, you don't actually need to use interrupts at all - you just look at the state of the inupt pin, and use that to decide whether to blink or not.

In fact, this is somewhat preferable as you have no chance of getting out of sync if you should miss an interrupt. For simple LED flashing, you probably wouldn't even need debouncing...