DEPR: Series constructor fastpath keyword

[jbrockmendel]

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[mroeschke]

Do we need/have an alternative for the fastpath constructor internally?

[jbrockmendel]

we now use _constructor_from_mgr

[mroeschke]

Thanks @jbrockmendel

[rhshadrach]

This patch may have induced a performance regression. If it was a necessary behavior change, this may have been expected and everything is okay.

Please check the links below. If any ASVs are parameterized, the combinations of parameters that a regression has been detected appear as subbullets.

• indexing.NumericSeriesIndexing.time_iloc_slice
  • dtype=<class 'numpy.float64'>; index_structure='unique_monotonic_inc'

Subsequent benchmarks may have skipped some commits. See the link below to see which commits are between the two benchmark runs where the regression was identified.

e22bfb3...66a54a3

[lithomas1]

@jbrockmendel

Is there an alternative for avoiding name validation now that fastpath is gone? I think this might be what's causing the regressions.

[jbrockmendel]

set result._name = name instead of passing it to the constructor