BUG: Regression - AmbiguousTimeError creating 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.

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

---

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

Pandas 1.25:
```python
import pandas as pd
dt = pd.to_datetime('2019-11-03 01:00:00-0700').tz_convert('America/Los_Angeles')
pd.DataFrame({'dt': dt, 'value': [1]})
#                          dt  value
# 0 2019-11-03 01:00:00-07:00      1
```
Pandas 1.3:
```python
import pandas as pd
dt = pd.to_datetime('2019-11-03 01:00:00-0700').tz_convert('America/Los_Angeles')
pd.DataFrame({'dt': dt, 'value': [1]})

#  File "pandas/_libs/tslibs/tzconversion.pyx", line 284, in pandas._libs.tslibs.tzconversion.tz_localize_to_utc
# pytz.exceptions.AmbiguousTimeError: Cannot infer dst time from 2019-11-03 01:00:00, try using the 'ambiguous' argument
```

#### Problem description

The `dt` object already has a timezone attribute, so it shouldn't be converting/inferring at all.

#### Expected Output

1.25 and 1.3.0 should have the same output.

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

<details>

INSTALLED VERSIONS
------------------
commit           : f00ed8f47020034e752baf0250483053340971b0
python           : 3.7.3.final.0
python-bits      : 64
OS               : Darwin
OS-release       : 20.5.0
Version          : Darwin Kernel Version 20.5.0: Sat May  8 05:10:33 PDT 2021; root:xnu-7195.121.3~9/RELEASE_X86_64
machine          : x86_64
processor        : i386
byteorder        : little
LC_ALL           : None
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.3.0
numpy            : 1.21.0
pytz             : 2021.1
dateutil         : 2.8.1
pip              : 21.1.2
setuptools       : 57.0.0
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : 2.9.1 (dt dec pq3 ext lo64)
jinja2           : None
IPython          : None
pandas_datareader: None
bs4              : None
bottleneck       : None
fsspec           : None
fastparquet      : None
gcsfs            : None
matplotlib       : 3.2.2
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pyxlsb           : None
s3fs             : None
scipy            : 1.7.0
sqlalchemy       : None
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
numba            : None


</details>
