bugfix: wrong usage of TClonesArray::GetEntries() that slows down L1 reconstruction

In a few places GetEntries() was used instead of GetEntriesFast().

The MR should fix this redmine issue: https://lxcbmredmine01.gsi.de/issues/2102

changed milestone to %APR21

approved this merge request

added BugFix Reconstruction labels

enabled an automatic merge when the pipeline for 8f20a3bc succeeds

Dear @se.gorbunov, @v.akishina,

you have been identified as code owner of at least one file which was changed with this merge request.

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added CodeOwners label

merged