[PWGEM] Revert "[PWGEM] LMee: Adding more DCA correlation histograms to various signals."

[hscheid]

Reverts #15602

The above PR seems to break the MC analysis as the beauty histograms are defined twice:
Error from the HY test

[ERROR] SEVERE: Device dielectron-mc (561166) had at least one message above severity 7: Hash collision in HistogramRegistry "output"! Please rename histogram "Pair/bbbar/b2l_b2l/uls/hDCAz1vsDCAz2" or "Pair/bbbar/b2l_b2l/uls/hDCAz1vsDCAz2".

This can be traced back to
This defines the histogram for charm:

O2Physics/PWGEM/Dilepton/Core/DileptonMC.h

Line 549 in ed0e19a

fRegistry.add(std::format("Pair/ccbar/c2l_c2l/{0}hDCAz1vsDCAz2", strSign), "DCA_{z,1} vs DCA_{z,2}", o2::framework::kTH2F, {axis_dca_track1, axis_dca_track2}, true);

Then here the charm histograms are copied to the beauty histograms:

O2Physics/PWGEM/Dilepton/Core/DileptonMC.h

Line 553 in ed0e19a

fRegistry.addClone("Pair/ccbar/c2l_c2l/", "Pair/bbbar/b2l_b2l/");

and here it is defined again:

O2Physics/PWGEM/Dilepton/Core/DileptonMC.h

Line 584 in ed0e19a

fRegistry.add(std::format("Pair/bbbar/b2l_b2l/{0}hDCAz1vsDCAz2", strSign), "DCA_{z,1} vs DCA_{z,2}", o2::framework::kTH2F, {axis_dca_track1, axis_dca_track2}, true);

[github-actions]

O2 linter results: ❌ 263 errors, ⚠️ 241 warnings, 🔕 0 disabled

[alibuild]

Auto-approving on behalf of @hscheid.