Update the expected DataSet plot title after xarray 2022.6.0

[maximlt]

One test started to fail after the release of xarray 2022.6.0 a couple of days ago. The title set to a plot made from an xarray object is defined by relying on an internal xarray function, this was added in #659. Apparently something changed in xarray, I actually didn't see any obvious change in the particular function that was called so that may be at another level, anyway the scalar coords displayed in the title are not ordered in the same way after the last release. In the failing test 'y = 0, x = 0, time = 0, band = 0' was replaced by 'time = 0, y = 0, x = 0, band = 0'. The former, i.e. the newer title, appears to be more accurate as respecting the order of the coords declared in one of the original DataArray:

hvplot/hvplot/tests/testoptions.py

Line 478 in 912b70f

coords={'time': [0, 1], 'y': [0, 1], 'x': [0, 1], 'band': [0, 1]},

I've simply updated the test to not fail with the newest releases of xarray, and still pass with the older ones.

[maximlt]

Merging, it's a minor change to the test suite that reflects that hvplot is in line with the output of the .plot API of xarray, and it's preventing other test runs to pass.