LTV crash fix and high mld fixes for multichannel files

[x] MLD improvements for Multi-channel 5_1 at 384 kbps, 48kHz in, 48kHz out, 7_1_4 out
[x] Crash fix for LTV stream: ltv-stereo at 24.4 kbps, 48kHz in, 48kHz out, DTX on

• EVS 26.444 BE test passes.
• decoder pytests:
  MLD scores:
  Original inputs: 562 failed, 374 skipped
  MLD > 10: 3
  MLD > 5 : 27
  MLD < 5 : 532
  +10dB inputs: 562 failed, 374 skipped
  MLD > 10: 44
  MLD > 5 : 139
  MLD < 5 : 379
  -10dB inputs: 562 failed, 374 skipped
  MLD > 10: 0
  MLD > 5 : 7
  MLD < 5 : 555
• encoder pytests results:
  MLD scores:
  Original inputs: 562 tests:
  MLD > 10: 18
  MLD > 5 : 67
  MLD < 5 : 477
  +10dB inputs: 562 tests:
  MLD > 10: 69
  MLD > 5 : 122
  MLD < 5 : 371
  -10dB inputs: 562 tests:
  MLD > 10: 5
  MLD > 5 : 24
  MLD < 5 : 533