SLB: B2LNuGamma Run 3

We propose to:

• delete the HLT2 and Sprucing lines for B(c)+ → l+ ν_l γ (→ e+ e-) with downstream electrons, both for l = μ and l = e;
• change the μ pt_min in the make_b2mugammanu_cnvll builder from 300 MeV to 1000 MeV;
• change the B vchi2pdof_max in the make_b2lllnu builder from 4 to 16 only for btolgammanu lines.