Avoid InheritsFrom in CCDB object extraction

TClass::InheritsFrom("TObject") on an STL collection such as
std::vector<o2::detectors::AlignParam> makes cling instantiate the class and
read a large part of the ROOT module data. IsTObject() gives the same answer
without this. In o2-sim, which fetches the alignment this way, this saves about
150 MB (16 workers, peak PSS 6384 -> 6215 MB) with bit-identical hits.

Author: sawenzel

CCDB/src/CcdbApi.cxx

@@ -1008,7 +1008,8 @@ void* CcdbApi::extractFromTFile(TFile& file, TClass const* cl, const char* what)
   auto result = object;
   // We need to handle some specific cases as ROOT ties them deeply
   // to the file they are contained in
-  if (cl->InheritsFrom("TObject")) {
+  // IsTObject avoids InheritsFrom, which makes cling instantiate STL collection classes
+  if (cl->IsTObject()) {
     // make a clone
     // detach from the file
     auto tree = dynamic_cast<TTree*>((TObject*)object);