Remove IC-BWE obsolete code

• Related issues: #2367 (closed)
• Requested reviewers:

Reason why this change is needed

• IC-BWE obsolete code

Description of the change

• remove obsolete code around calling the IC-BWE encoder
  • code is a duplication from icbwe_dft_stereo_param()
  • remove obsolete computation of scaling factor q_new_swb_speech_buffer - the buffer new_swb_speech_buffer_fx_16 is used as a temporary one and has no meaningful values at the time when the scaling factor is currently computed
  • code is not present in FLP
• align function names with FLP + formatting

Affected operating points

• All is BE.

Closes #2367 (closed)