Flaky Test Case in RPN Label Encoder and ROI Sampler

[ariG23498]

Description

There's a flaky test case in the rpn_label_encoder_test.py, specifically linked here. The flakiness appears to be due to the use of the random API, which introduces non-deterministic behavior in test outcomes.

Problem Demonstration

A deeper investigation into the issue is documented in this Colab Gist, which outlines how the random API's usage is leading to inconsistent test results.

CC: @divyashreepathihalli

[ariG23498]

Adding to the previously stated test failing, I think test_roi_sampler_small_threshold has a similar behavoiur.

Reproduction of the error: GitHub Gist