Add LbToLambdaGamma downstream Hlt2 line

The last rate using expected 2024 min bias gave

Line:	 Hlt2RD_LbToLambdaGamma_DDDecision                        	 Incl: 0.1254 +/- 0.0378 kHz,	Excl: 0.1254 +/- 0.0378 kHz

So I have added a presale of 0.8 which should put it in budget

Depends on lhcb-datapkg/ParamFiles!94 (merged)