WIP: Merge XiczToLambdaKPi lines; improve Sigma lines

This is an attempt to merge \Xi_c^0\to\Lambda K^-\pi^+ lines as discussed in !1286 (closed)

I had a look at the respective simulation samples (26104183 on (L)DST, not the stripping filtered). The outcome is detailed in this spreadsheet. It turns out that both selections were not really optimal. The selection proposed here should improve the signal yield (I guess 50%, likely more) while retention rates are low.

Since time is really running out, I don't know how to proceed best. @lohenry, @jfu please have a look and let me know if the changes make sense. Especially since they also affect the other Lhh samples.

Retentions/timings

StrippingReport                                                INFO Event 25000, Good event 25000
 |                                              *Decision name*|*Rate,%*|*Accepted*| *Mult*|*ms/evt*|
 |_StrippingGlobal_                                            |  1.9440|       486|       |  30.450|
 |_StrippingSequenceStreamCharm_                               |  1.9440|       486|       |  30.428|
 |!StrippingXicpToSpKmPipLine_TIMING                           |  0.2280|        57|  1.561|   1.447|
 |!StrippingXicpToSzKzPipLine_TIMING                           |  0.1240|        31|  2.484|   0.182|
 |!StrippingXiczToSzKmPipLine_TIMING                           |  0.6040|       151|  2.742|   0.580|
 |!StrippingXic2LambdaKPi_XicpLine_TIMING                      |  0.4520|       113|  2.717|   0.065|
 |!StrippingHc2V02H_Xic2LambdaPiPiLLLine_TIMING                |  0.1880|        47|  1.894|   0.066|
 |!StrippingHc2V02H_Xic2LambdaPiPiDDLine_TIMING                |  0.1560|        39|  1.692|   0.066|
 |!StrippingHc2V02H_Xic2LambdaKKLLLine_TIMING                  |  0.1120|        28|  1.964|   0.055|
 |!StrippingHc2V02H_Xic2LambdaKKDDLine_TIMING                  |  0.0600|        15|  1.733|   0.047|
 |!StrippingHc2V02H_Xic2LambdaKPiLLLine_TIMING                 |  0.2240|        56|  1.821|   0.062|
 |!StrippingHc2V02H_Xic2LambdaKPiDDLine_TIMING                 |  0.1280|        32|  2.062|   0.059|
 |!StrippingHc2V02H_Xic2LambdaPiKLLLine_TIMING                 |  0.1680|        42|  1.476|   0.058|
 |!StrippingHc2V02H_Xic2LambdaPiKDDLine_TIMING                 |  0.2000|        50|  1.560|   0.053|