text: Title: BUG: Series constructor from dictionary drops key (index) levels when not all keys have same number of entries
  Body: ### Pandas version checks
  
  - [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 [main branch](https://pandas.pydata.org/docs/dev/getting_started/install.html#installing-the-development-version-of-pandas) of pandas.
  
  
  ### Reproducible Example
  
  ```python
  import pandas as pd
  
  pd.Series({("l1",):"v1", ("l1","l2"): "v2"})
  # Out[30]: 
  # l1    v1
  # l1    v2
  # dtype: object
  
  # the reason is that the Series constructor uses internally MultiIndex.from_tuples in the following way (note that the input is a tuple of tuples!):
  pd.MultiIndex.from_tuples((("l1",), ("l1","l2")))
  # Out[32]: 
  # MultiIndex([('l1',),
  #             ('l1',)],
  #            )
  
  # compare to the following which produces the expected result:
  pd.MultiIndex.from_tuples([("l1",), ("l1","l2")])
  # Out[33]: 
  # MultiIndex([('l1',  nan),
  #             ('l1', 'l2')],
  #            )
  
  # Note: this was tested with latest release and current master
  ```
  
  
  ### Issue Description
  
  When calling the `Series` constructor with a dict where the keys are tuples, a series with `MulitIndex` gets created. However, if the number of entries in the keys is not the same, key entries from keys with more than the minimum number get dropped. This is in several ways problematic, especially if this produces duplicated index values / keys which is not expected because it was called with a dict (which has per definition unique keys).
  
  ### Expected Behavior
  
  The `MultiIndex` of the new series has nan-padded values.
  
  ### Installed Versions
  
  <details>
  
  INSTALLED VERSIONS
  ------------------
  commit                : 0691c5cf90477d3503834d983f69350f250a6ff7
  python                : 3.10.16
  python-bits           : 64
  OS                    : Linux
  OS-release            : 6.8.0-51-generic
  Version               : #52~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Dec  9 15:00:52 UTC 2
  machine               : x86_64
  processor             : x86_64
  byteorder             : little
  LC_ALL                : None
  LANG                  : de_DE.UTF-8
  LOCALE                : de_DE.UTF-8
  
  pandas                : 2.2.3
  numpy                 : 2.2.1
  pytz                  : 2024.2
  dateutil              : 2.9.0.post0
  pip                   : 24.2
  Cython                : None
  sphinx                : None
  IPython               : None
  adbc-driver-postgresql: None
  adbc-driver-sqlite    : None
  bs4                   : None
  blosc                 : None
  bottleneck            : None
  dataframe-api-compat  : None
  fastparquet           : None
  fsspec                : None
  html5lib              : None
  hypothesis            : None
  gcsfs                 : None
  jinja2                : None
  lxml.etree            : None
  matplotlib            : None
  numba                 : None
  numexpr               : None
  odfpy                 : None
  openpyxl              : None
  pandas_gbq            : None
  psycopg2              : None
  pymysql               : None
  pyarrow               : None
  pyreadstat            : None
  pytest                : None
  python-calamine       : None
  pyxlsb                : None
  s3fs                  : None
  scipy                 : None
  sqlalchemy            : None
  tables                : None
  tabulate              : None
  xarray                : None
  xlrd                  : None
  xlsxwriter            : None
  zstandard             : None
  tzdata                : 2024.2
  qtpy                  : None
  pyqt5                 : None
  
  </details>
  