plot_pair axis labels no longer include coords

[lhelleckes]

Describe the bug
Using plot_pair with a selection of coords, I got a plot where the axis labels only show var_names, so different coords get the same label.

To Reproduce

test_idata = arviz.from_dict(
    posterior = dict(a=numpy.random.rand(1, 10, 3), b=numpy.random.rand(1 ,10, 1)),
    dims={'a':['a_dim',]},
    coords=dict(a_dim=['test_A', 'test_B', 'test_C'])
)
arviz.plot_pair(
    test_idata, 
    coords=dict(a_dim=['test_A', 'test_B']),
    kind='kde'
);

Expected behavior
Axis labels should also include the coords to be unique (in this case a_test_A or similar).

Additional context
arviz_version : 0.11.0

[OriolAbril]

I will look into it asap. This is completely unexpected :/. Does this already happen with 0.11 or on development version? (both will show 0.11 as version)

[lhelleckes]

I tested it with the 0.11 release. Thanks for looking into it!