Test if overlayfs is affected by the DAC bug wrt. incremental upgrades changing UID/GID

The bug was described on #13426 (closed).

If overlayfs is not affected, then as long as we don’t complete the rest of #15281 strictly before #8415, then we can reject the parent ticket (#15407 (closed)).

Parent Task: #8415

Related issues

Related to #13426 (closed)
Blocks #16209

Original created by @intrigeri on 15689 (Redmine)

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