BUG: get_indexer_for() does not always return list of indeces
### 

- [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
import numpy as np

interval_index = pd.IntervalIndex.from_tuples([(1.0, np.inf), (-np.inf, 0.0), (0.0, 1.)], name='interval')
foo_index = pd.Index([1, 2, 3], name='foo')


multi_index = pd.MultiIndex.from_product([foo_index, interval_index])

print(multi_index.get_level_values('foo').get_indexer_for([2]))
print(multi_index.get_level_values('interval').get_indexer_for([pd.Interval(-np.inf, 0.0)]))


multi_index = pd.MultiIndex.from_product([interval_index, foo_index])

print(multi_index.get_level_values('foo').get_indexer_for([2]))
print(multi_index.get_level_values('interval').get_indexer_for([pd.Interval(-np.inf, 0.0)]))
```


### Issue Description

`get_indexer_for()` does not return a list of indeces as described in the docs but a mask like list under some circumstances.

As far as I have investigated, the behavior occurs if all of the following conditions are met:

* the index is a `MultiIndex`
* the level in question is a `IntervalIndex`
* the level in question is not the first level of the `MultiIndex`

The script above outputs
```
[3 4 5]
[0 1 0 0 1 0 0 1 0]
[1 4 7]
[3 4 5]
```

### Expected Behavior

Expected output
```
[3 4 5]
[1 4 7]
[1 4 7]
[3 4 5]
```

### Installed Versions

<details>

INSTALLED VERSIONS
------------------
commit           : 3a6d4cd01d076762ad60c5fd6551012cb72a808d
python           : 3.9.7.final.0
python-bits      : 64
OS               : Linux
OS-release       : 5.4.0-88-lowlatency
Version          : #99-Ubuntu SMP PREEMPT Thu Sep 23 18:30:52 UTC 2021
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : None
LANG             : de_DE.UTF-8
LOCALE           : de_DE.UTF-8

pandas           : 1.4.0.dev0+933.g3a6d4cd01d
numpy            : 1.21.2
pytz             : 2021.3
dateutil         : 2.8.2
pip              : 21.2.4
setuptools       : 58.0.4
Cython           : None
pytest           : 6.2.5
hypothesis       : 6.23.3
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : None
IPython          : None
pandas_datareader: None
bs4              : None
bottleneck       : None
fsspec           : None
fastparquet      : None
gcsfs            : None
matplotlib       : None
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pyxlsb           : None
s3fs             : None
scipy            : None
sqlalchemy       : None
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
numba            : None

</details>
