BUG: DatetimeIndex.intersection with non-anchored freq
### 

- [X] I have checked that this issue has not already been reported.

- [X] I have confirmed this bug exists on the [latest version](https://pandas.pydata.org/docs/whatsnew/index.html) of pandas.

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


### Reproducible Example

```python
import pandas as pd

off = pd.offsets.CDay(1, False)

ts = pd.Timestamp("2021-10-13 09")
ts2 = ts + pd.Timedelta("1 hour")

dti = pd.date_range(start=ts, periods=10, freq=off)
dti2 = pd.date_range(start=ts2, periods=10, freq=off)

assert set(dti).intersection(set(dti2)) == set()  # yep!

res = dti.intersection(dti2)
assert len(res) == 0  # nope!
```


### Issue Description

_can_fast_intersect is wrong for the non-anchored case, returning `self.freq.n == 1` which is not sufficient in this case.  It may be that we just need to return False for non-anchored.

### Expected Behavior

The intersection should be empty

### Installed Versions

master