BUG: Behaviour of numeric_only in aggregation methods like sum depends on length of dataframe.
- [x] I have checked that this issue has not already been reported.

- [x] 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

df = pd.DataFrame({'non_numeric': 10000*[pd.Timedelta(10)], 'numeric': 10000*[1]})
# Summing over axis 1 with numeric_only=True works as expected
assert_series_equal(df.sum(axis=1, numeric_only=True), df.numeric, check_names=False)
# Summing with the default numeric_only=None only works if df has <= 8192 = 2**13 rows
sample = df.sample(8192)
assert_series_equal(sample.sum(axis=1), sample.numeric, check_names=False)
# Summing over the whole dataframe we get a SystemError
df.sum(axis=1)
# The following also produces a SystemError
sample['numeric_2'] = 1
sample.sum(axis=1)
# The following does not produce a SystemError
sample.sample(1).sum(axis=1)

```

#### Problem description

In previous pandas versions the last line does not throw a TypeError. The default numeric_only=None will only sum over the numeric columns of the dataframe. 
In pandas 1.2.4 this is the case if the length of the dataframe is <= 8192 = 2**13. As soon as the length exceeds 8192 we get a SystemErrorbecause it tries to sum a Timedelta column and an int column. We also get a SystemError when df has more than one numeric column. Then the sum only works if the length of the dataframe is 1

The behaviour of sum is the same for other aggregation methods like mean.

#### Expected Output

I expect df.sum(axis=1) to return a series whose entries are the sum of the numeric columns of the dataframe along the axis 1 as is the case for dataframes of length <= 8192.

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

<details>

INSTALLED VERSIONS
------------------
commit           : 2cb96529396d93b46abab7bbc73a208e708c642e
python           : 3.9.4.final.0
python-bits      : 64
OS               : Linux
OS-release       : 3.10.0-693.5.2.el7.x86_64
Version          : #1 SMP Fri Oct 20 20:32:50 UTC 2017
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : None
LANG             : en.UTF-8
LOCALE           : None.None

pandas           : 1.2.4
numpy            : 1.20.1
pytz             : 2021.1
dateutil         : 2.8.1
pip              : 21.0.1
setuptools       : 52.0.0.post20210125
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 2.11.3
IPython          : 7.22.0
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>
