PerfMonComps: Update PerfMonMT CA configuration

This MR should fix the failing CA-based simulation ART tests in the latest nightly. The problem originated from two MRs that did play nicely with each other: !47011 (merged) and !47014 (merged). Originally we were inserting PerfMonMTAlg to the standard AthAlgSeq. After the former, this algorithm is now being added to AthBeginSeq but by default a bare ComponentAccumulator doesn't know about this. So, things needed to be adjusted a little bit to accomodate that. Let me cc @jchapman and @tadej so that they're aware.

Also, the legacy configuration allows one to insert an algorithm to anywhere in a sequence (by index). Admittedly, this can be a little fiddly but it was nice to have. This doesn't seem to be possible in the new configuration from a quick glance. Maybe @wlampl has an idea on that.