Resolve "Simplify "strong limiting" logic in limiter"

• Related issues: #893 (closed)
• Requested reviewers: @vaclav

Reason why this change is needed

While writing the limiter specification, I noticed that the logic used to trigger strong limiting can be simplified without affecting BE. The resulting code is easier to understand and to describe in the spec.

Description of the change

Code around the limiter function detect_strong_saturations was simplified, but remains logically equivalent.

Affected operating points

Everything BE in MR pipelines and in long testvector pipeline (https://forge.3gpp.org/rep/ivas-codec-pc/ivas-codec/-/jobs/182000).