text: Title: Unique Operation fails on dataframe repartitioned using set index after resetting the index
  Body: 
  
  **Describe the issue**:
  
  **Minimal Complete Verifiable Example**:
  
  ```python
  import pandas as pd
  import dask.dataframe as dd
  
  data = {
      'Column1': range(30),
      'Column2': range(30, 60)
  }
  
  pdf = pd.DataFrame(data)
  
  # Convert the Pandas DataFrame to a Dask DataFrame with 3 partitions
  ddf = dd.from_pandas(pdf, npartitions=1)
  ddf = ddf.set_index('Column1', sort=True, divisions=[0,10,20,29], shuffle='tasks')
  
  print(ddf.npartitions)
  
  ddf = ddf.reset_index()
  
  unique = ddf['Column1'].unique().compute()
  ```
  
  **Anything else we need to know?**:
  
  **Environment**:
  
  - Dask version: 2024.4.2
  - Python version: 3.10
  - Operating System: Mac OSx
  - Install method (conda, pip, source): dask[dataframe]
  