When running the incr_backup csuite test with the -p preserve flag, we retain test artefacts but in a nested manner - WT_TEST.incr_backup/WT_TEST.incr_backup... since main calls run_test three times.

These artefacts should instead be generated alongside the WT_TEST home directory.

To resolve this, we need to rethink the directory structure and/or naming convention to ensure the test directory is preserved across all three tests without creating nested directories.