Truncate long lines in repr of coords

[max-sixty]

MCVE Code Sample

xr.DataArray(coords=dict(a=' '.join(['hello world' for _ in range(100)])))

<xarray.DataArray ()>
array(nan)
Coordinates:
    a        <U5999 'hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello  world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world hello world'

Expected Output

<xarray.DataArray ()>
array(nan)
Coordinates:
    a        <U5999 'hello world ... hello world'

Problem Description

I think mostly the same as #1319 but for coords

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.7.3 | packaged by conda-forge | (default, Jul 1 2019, 21:52:21) [GCC 7.3.0] python-bits: 64 OS: Linux OS-release: [...] machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.utf8 LOCALE: en_US.UTF-8 libhdf5: 1.10.5 libnetcdf: 4.7.1

xarray: 0.15.0
pandas: 0.25.3
numpy: 1.17.3
scipy: 1.3.2
netCDF4: 1.5.3
pydap: None
h5netcdf: 0.7.4
h5py: 2.10.0
Nio: None
zarr: None
cftime: 1.0.4.2
nc_time_axis: None
PseudoNetCDF: None
rasterio: None
cfgrib: None
iris: None
bottleneck: 1.2.1
dask: 2.7.0
distributed: 2.7.0
matplotlib: 3.1.2
cartopy: None
seaborn: 0.9.0
numbagg: None
setuptools: 41.6.0.post20191101
pip: 19.3.1
conda: None
pytest: 5.2.2
IPython: 7.9.0
sphinx: 2.2.1

[keewis]

this should have been closed by #3900