String/object dunder/operator methods do not delegate to the right backend in 2.26.0

```
import dask.array as da

a = da.from_array(["a", "b", ".", "e"])
print(a == ".")

# 2.26.0: False
# 2.25.0: dask.array<eq, shape=(4,), dtype=bool, chunksize=(4,), chunktype=numpy.ndarray>
```

Is this expected in `2.26.0`? I can't find relevant changelog for this.

Environment:
* Dask version: 2.26.0
* Python version: 3.8
* Install method (conda, pip, source): conda/pip