CLN: use lib.no_default instead of lib.NoDefault in reshape.pivot

[jbrockmendel]

In core.reshape.pivot we have a couple places where a default kwarg is lib.NoDefault where the idiomatic usage would be lib.no_default. I assumed this was just a typo, but when I tried changing it, some tests broke. Need to track down what's going on there.

[Charlie-XIAO]

@jbrockmendel Seems that in pandas/core/frame.py and pandas/tests/reshape/test_pivot_multilevel.py there are also such typos, maybe this is the reason b/c they explicitly pass lib.NoDefault when calling pivot. I tried changing those as well and the test cases pass. Are you already working on a PR? Otherwise I can help.

Edit: since there is no reply and I did not find an existing PR for this, I will just go ahead.