fix: improve `PossiblyNoBeam` assignment for RG-A Sp19 #178

Job	Run time
get_datasets	12s
groovy_vs_cpp (pass1/rga_fa18_inbending)	33m 26s
groovy_vs_cpp (pass1/rga_fa18_outbending)	37m 27s
groovy_vs_cpp (pass1/rga_sp19)	24m 29s
groovy_vs_cpp (pass1/rgb_fa19)	24m 28s
groovy_vs_cpp (pass1/rgb_sp19)	50m 39s
groovy_vs_cpp (pass1/rgb_wi20)	35m 26s
groovy_vs_cpp (pass1/rgc_su22)	1h 13m 14s
groovy_vs_cpp (pass1/rgk_fa18_6.5GeV)	20m 51s
groovy_vs_cpp (pass1/rgk_fa18_7.5GeV)	29m 3s
groovy_vs_cpp (pass1/rgm_fa21)	1h 43m 0s
groovy_vs_cpp (pass2/rga_sp19)	8m 52s
report	1s
	7h 21m 8s

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