Remove tmp_idx_container_repos_on_non_migrated index

🔥 Problem

The tmp_idx_container_repos_on_non_migrated index was created in !83980 (merged) to support a function that would check if all image repositories of a given scope was migrated.

This index needs to be removed once that function is not needed anymore. The index should be empty: all the older existing image repositories are considered imported/migrated.

Milestone tentatively set to %15.5 given the timeline found in: &5523 (closed)

Implementation Guide

Remove the tmp_idx_container_repos_on_non_migrated index. This index was updated in !95871 (merged) to tmp_index_container_repos_on_non_migrated.

Remove tmp_index_container_repos_on_non_migrated.