Resolve "USAN: index out of bounds in MC bitrate switching for decoding to STEREO"

• Related issues: #1005 (closed)
• Requested reviewers:

Reason why this change is needed

Clang usan sanitizer test in pipeline found an error:

lib_dec/ivas_jbm_dec.c:2588:28: runtime error: index 8 out of bounds for type 'int16_t [8]'
SUMMARY: UndefinedBehaviorSanitizer: out-of-bounds-index lib_dec/ivas_jbm_dec.c:2588:28 in 

Link to test pipeline: https://forge.3gpp.org/rep/ivas-codec-pc/ivas-codec/-/jobs/218857

Caused by wrong update of the TC buffer state in the MC rate switch reconfiguration

Description of the change

Fix TC buffer update on a MC rate switch

Affected operating points

• BE
• Produced bitstream is BE compared to previous state.

Related to #1005 (closed)