BUG: Index of an empty Series cannot be compared to a Timestamp anymore
- [Y] I have checked that this issue has not already been reported.

- [Y] I have confirmed this bug exists on the latest version of pandas.

- [ ] (optional) I have confirmed this bug exists on the master branch of pandas.

---

#### Code Sample, a copy-pastable example

```python
def test_series_timestamp_comparison():
    my_series = pd.Series([],  dtype=np.float64)
    date = pd.Timestamp('2015-07-15 00:00:00')

    res = my_series.index < date
    assert res.dtype == bool
    assert len(res) == 0
```

#### Problem description

In pandas 1.1.2 the above test passes, while in 1.1.3 it throws an error on line  5:

Error in 1.1.3:
TypeError: '<' not supported between instances of 'numpy.ndarray' and 'Timestamp'

As far as I can tell, this started to occur because of a change in pandas.core.indexes.base._make_comparison_op,
which change was added by this PR: https://github.com/pandas-dev/pandas/pull/36440

My question is if the new behaviour is legit for the above comparison, is it expected?

In 1.1.2 this comparison didn't fail, because it would end up in
```
        else:
            with np.errstate(all="ignore"):
                result = op(self._values, np.asarray(other))
```
which was changed to:
```
        elif is_interval_dtype(self.dtype):
            with np.errstate(all="ignore"):
                result = op(self._values, np.asarray(other))
```
and the else part started to use ops.comparison_op which now fails in the above example (since is_interval_dtype(self.dtype) is false for the above case).

A bit more background: the above comparison is used when subselecting data in the series without knowing whether the input series has data in it or not. So e.g.:
```
my_series[my_series.index < date] = 0.4
```

Apologies if this question has been raised, I couldn't find anything similar in Open Issues.

#### Output of ``pd.show_versions()``

<details>

python           : 3.7.4.final.0
pandas           : 1.1.3
numpy            : 1.19.2

</details>
