Revisit bam filtering

[jayhesselberth]

In particular, why do we have this line:

https://github.com/rnabioco/aa-tRNA-seq-pipeline/blame/a3e5a9f766c641d9932cfc50009c7cae7446dbcd/workflow/rules/aatrnaseq.smk#L110

Do you remember, @MSajek ?

[MSajek]

to filter out tRNAs with truncated 5'end