Consider disabling by default or removing Chain.capture in build_runner

[kevmoo]

build/build_runner/lib/src/generate/build_impl.dart

Line 265 in 42c4fde

Chain.capture(() async {

In one case, seems to add 8% to build times

[natebosch]

+1 to remove

[jakemac53]

Ya I am in favor of removing as well.

[natebosch]

We had some discussion where we assumed that this was mainly capturing stack traces for exceptions which happen within the build_runner package, not within builders. When I look at #448 and it's related issue #427 it points to this helping with stack traces from exceptions within builders.

It's possible this is no longer the case if something has change in runBuilder, but we should check.

Worst case scenario is instead of remove it we default the when to false and add a flag to turn it back on specifically for Builder authors to diagnose issues.

The capture was added in #62 but there isn't discussion on why it was chosen instead of runZoned

[natebosch]

OK, I think #550 effectively shifts the responsibility into runBuilder. We don't have the Chain.capture there, but probably don't need it since the stack trace should be much more focused at that point since it should really only be stuff in the builder code. Removing this altogether is right choice.