BulkApi test: TFile used by TTreeReader needs to be delete last.
BulkApi test: TFile used by TTreeReader needs to be delete last.

This fixes Issue #10012.

TTreeReader is not in any cleanup list but retain a reference to the TTree and thus the TTree (and its TFile) must be deleted
after the TTreeReader object(s) using them

The original problem was in BulkApiMultipleTest_stdRead_Test and the other test were also updated to apply the same pattern to the rest of the file for consistency.

The long story is that (almost) all the tests were faulty but most were not a problem because instead of explicitly
deleting the TFile, they let the `TFile` be deleted at the end of the process.  The faulty order is:

1. Create `TFile`
2. Create `TTreeReader`
3. Delete `TFile`
4. Delete `TTreeReader`

which happens with:
```
{
   TFile *hfile = TFile::Open(....);
   ...
   myReader("T", hfile);
   ....
   delete hfile;  // This is the problem, this is "too soon".
}
```

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root