[query/plot] removes "chr" prefix for manhattan plot x-axis labels

[iris-garden]

Fixes #13952.

[danking]

this next line is gonna fail b/c the contains aren't valid anymore. I think you'll have to replace this at the very latest moment: when you construct the major_label_overrides.

[iris-garden]

tested the latest version of the change by copying and running the plotting tutorial notebook; verified that the code as is generates a visually identical manhattan plot, and then added this line before the manhattan plot is displayed:

gwas = gwas.key_by(locus = hl.locus("chr" + gwas.locus.contig, hl.int(gwas.locus.position / 2), reference_genome="GRCh38"))

and the output looked like this (the big gaps between the points for each chromosome come from dividing by 2 above, which is a quick-and-dirty trick to make sure none of the loci have position values that are too large for GRCh38):

[danking]

Do you have unpushed changes?

This fails:

In [4]: gwas = hl.balding_nichols_model(1,100, 1, reference_genome='GRCh38').rows().annotate(p_value=10 **
   ...: -hl.rand_int32(1, 8))
   ...: hl.plot.manhattan(gwas.p_value, gwas.locus).show()

_

[iris-garden]

@danking oh yep, sorry! github was down but it said the changes had pushed from the command line, now it's fixed