[bug-fix] Fix sequence length buffer truncate

[ervteng]

Proposed change(s)

Fixed an issue where if 80% of the buffer isn't a multiple of sequence length, we'll get weird sequences in the buffer. Only affects SAC with LSTM.

Types of change(s)

• Bug fix
• New feature
• Code refactor
• Breaking change
• Documentation update
• Other (please describe)

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)
• Updated the documentation (if applicable)
• Updated the migration guide (if applicable)

Other comments

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[montplaisir]

Thank you for your submission!
Your changes were ported to PR #6301.