feat: turn off ak's typetracer _new checks during optimize

[martindurant]

Will have no effect until scikit-hep/awkward#3054 is out

@lgray , any other places we need this optimisation?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 83.33333% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 93.01%. Comparing base (8cb8994) to head (dcd1f65).
Report is 60 commits behind head on main.

Files	Patch %	Lines
src/dask_awkward/lib/inspect.py	76.47%	4 Missing ⚠️
src/dask_awkward/lib/utils.py	90.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #486      +/-   ##
==========================================
- Coverage   93.06%   93.01%   -0.06%     
==========================================
  Files          23       23              
  Lines        3290     3336      +46     
==========================================
+ Hits         3062     3103      +41     
- Misses        228      233       +5     

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[lgray]

During dak.necessary_columns as well. Though that has some slowness that's kind of strange but different, it hasn't been high priority. This will help, of course.

[jpivarski]

If you specify the lines of code that should be avoided, I'll add them to this PR (with only one global switch for all).

[martindurant]

During dak.necessary_columns as well.

OK, but that's not actually something we've been talking about in our benchmarking recently. I suppose the columns opt is actually the only place we need this right now (although it would be nice throughout graph build time too). I wouldn't be opposed to a public function that can turn the flag and keep it that way for the whole session.

[lgray]

Yeah I haven't fully thought through or experienced the user-side lifecycle of necessary_columns... I have no idea if people use it a lot directly and if it needs to be snappy.

[martindurant]

OK, will merge this now, and we can add more blocks or set a global state in the future, if we decide.