Update heartbeat behavior

[MGaetan89]

Description

This PR updates the behavior of the heartbeat to match what was decided in the last API sync.

Changes made

• Change the heartbeat period to 30 seconds.
• Keep the heartbeat active when the player is paused.

Checklist

• Your branch has been rebased onto the main branch.
• APIs have been properly documented (if relevant).
• The documentation has been updated (if relevant).
• New unit tests have been written (if relevant).
• The demo has been updated (if relevant).
• All pull request status checks pass.

[github-actions]

Code Coverage

Overall Project	53.21% -0.01%	🟢
Files changed	97.3%	🟢

Module	Coverage
:pillarbox-core-business	81.95%	🟢
:pillarbox-player	59.07% -0.02%	🟢

Files

Module	File	Coverage
:pillarbox-core-business	CommandersActStreaming.kt	95.31%	🟢
:pillarbox-player	Heartbeat.kt	98.52%	🟢
	QoSCoordinator.kt	86.22%	🟢
	PillarboxExoPlayer.kt	80.61% -0.33%	🟢
	PillarboxEventsDispatcher.kt	62.23%	🟢
	QoSEventsDispatcher.kt	0%	🟢