Avoid having undefined props on tab audio indicator

[cezaraugusto]

Test plan:

• Indicator for audio must show if there's audio/video playing
• Mute indicator must show show if there's audio/video playing
• They should remain persistent while audio/video is playing

---

Some props on audio indicator (AudioTabIcon component) are undefined at some points possibly leading to unexpected behavior when the tab is idle (see #8249).

• We should coerce all truthy/falsy values to boolean;
• Since spec for tabs are now well defined, we should add a new breakpoint value for icon to be visible (it currently shows only when no breakpoint matches).

[bsclifton]

Fixed with #8273