Final quick muting phase after many lost frames incorrectly implemented in PhaseECU

Bug description

Muting variable *beta_mute is mistakenly decreased every band k, instead of every 20ms frame.

Variable *beta_mute controls a fast muting phase after a very long error burst (200ms or longer ). (a burst length typically not tested in the subjective tests tests)

Increase on this line: https://forge.3gpp.org/rep/ivas-codec-pc/ivas-codec/-/blame/main/lib_dec/FEC_HQ_phase_ecu.c#L421

Activated too often due to the band (k) loop here: https://forge.3gpp.org/rep/ivas-codec-pc/ivas-codec/-/blame/main/lib_dec/FEC_HQ_phase_ecu.c#L376

Misc: This long term muting bug for PhaseECU is also present in the EVS (Float/BASOP/ALT_BASOP) SW.

Ways to reproduce

Run a FER file with burst longer than 200ms. (e.g. 15 frames) for fullband high level music.

(Clear steps or refer to a failing automated test, e.g. with a pipeline link)