fix: prevent OpenCV from overriding our threading configuration

[chmjkb]

Description

We observed activity on all CPU cores despite manually configuring the thread pool. OpenCV's internal threading was activating all available cores, overriding our optimized thread configuration and resulting in worse performance.

Introduces a breaking change?

• Yes
• No

Type of change

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Documentation update (improves or adds clarity to existing documentation)
• Other (chores, tests, code style improvements etc.)

Tested on

• iOS
• Android

Testing instructions

Screenshots

Related issues

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings

Additional notes

[mkopcins]

LGTM