Resolve "Remove unused code in core-coder: HQ core"

• Related issues: #2300 (closed)
• Requested reviewers: @norvell

Reason why this change is needed

• In IVAS HQ core, LR-HQ core and 8 kHz I/O sampling rate are not supported and the related code can be removed.

Description of the change

• Remove unused code in IVAS HQ core.
• Removes cca 1,400 lines of source code.

Affected operating points

• All is BE.