Update default dataset to PCIC Blend, Tasmax

[QSparks]

The PNWNAmet 2015 Wind variable is the current default dataset displayed when starting the Daily Gridded Meteorological Datasets portal.

It is the only variable that is not clipped to the land, which causes it to appear slightly offset compared to the other datasets and doesn’t present as well visually.
I've proposed an update to Markus and he has suggested PCIC Blend, Tasmax as the starting variable.

A quick search of the repo suggests we would want to update this variable:

pdp/pdp/static/js/gridded_observations_map.js

Line 25 in 7029663

dataset: "wind_day_TPS_NWNA_v1_historical_19450101-20121231",

to use tasmax_day_PCIC_BLEND_v1_historical_19500101-20121231_Canada instead.