ENH: raise column number limit for user-completion or add warning
xref PR #35207

> Currently the user-completion (ipython "<tab>") on a dataframe with more than 100 columns will silently ignore some columns, letting an unaware user confused on whether data disapeared.
> 
> This is actually documented, and due to an arbitrary limit set to workaround a performance issue ( See #18587 )
> 
> Dataframe with more than 100 columns are quite common, so this can potentially affect and suprise many users. Therefore, I suggest to increase that limit to, say, 1000. In any case, it would probably be good to warn the user hitting that limit.
> 
> The attached quickfix raises the limit to 1000 and adds a warning beyond.

xref https://github.com/pandas-dev/pandas/pull/35207#issuecomment-663506204
> 
> This is still an arbitrary limit. adding a warning is maybe a good idea. Maybe this could be a pandas option to allow users to change this if required.
> 