perf test stat: Additional topdown grouping tests

Add a loop and helper function to avoid repetition, the loop uses
arrays so switch the shell to bash. Add additional topdown group tests
where a topdown event needs to be moved beyond others and the slots
event isn't first in the target group. This replicates issues that
occur on hybrid systems where the other events are for the cpu_atom
PMU. Test with both PMU and software events. Place the slots event
later in the event list.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250307023906.1135613-5-irogers@google.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>