improve irr chart visibility by selection union of labels to be displ…

[dsteedRTI]

This updates the readability of the irr chart by trimming down the labels on the X and Y axis to the union of labels used by the two users selected

[AstridKery]

Hey @dsteedRTI ! Just realized this must have fallen through the cracks. Definitely not a priority but we should probably resolve this before the end of the month.