Fix pause flags when recycling sound sources

Issue is due to pause flags getting recycled when new sound sources are used from the sound source pool.

This is a regression since 4.13, causing audio to pop.

1. Open attached project and press PIE.
2. Press the 'P' key to pause the game.
3. Press either the '1' key to reload the current level, or the '2' key to load a different level.

Outcome: The audio does not play when the level is loaded. The users must 'Pause' and then 'Unpause' the newly loaded level in order for the sounds to play as expected.

Expected The audio restarts when the level is loaded.