gh-107424: avoid using lambda functions in textwrap.indent()

[picnixz]

As mentioned by #107374 (comment), avoiding the use of a lambda function when no predicate is specified is expected to improve the performances.

The benchmarks reported on the issue corroborate this assumption. However, I would like to know if this is only because my laptop is dying (caching .append calls do not seem to help however).

I am waiting for changes to be verified before creating a NEWS entry (should I create it in conjunction to the already created one by @methane ?)

• Issue: Optimize textwrap.indent a bit more. #107424

[ghost]

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[bedevere-bot]

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[methane]

Our goal is not only maximize performance. And textwrap.indent() is not performance critical for most applications as far as I know.

In #107374, I made the code slightly simpler by removing generator.
On the other hand, this change makes maintenance cost little higher. We need to review and test the case for predicate is passed.
That's why I didn't incude this change in my PR.

(caching .append calls do not seem to help however).

Yes. It is old technique. Recent Python has little method call overhead. So append = L.append before loop has only little venefit.