[internal] Simplify PEX setup for ./pants run

[Eric-Arellano]

To implement #11619, we need to set --console-script on the requirements PEX, not the runner PEX. It does not work to set on the runner PEX because it will not have any distributions available.

In trying to fix that, I realized it is useful to simplify no longer having a requirements PEX vs. runner PEX. Originally, we split this so that the requirements PEX shared the cache between goals like test and lint. That is less relevant now that we first resolve from the constraints/lockfile, then extract the subset of deps - most of the heavy lifting will already be shared.

*#12806 was necessary to land before for this to work. Otherwise, the lockfile.pex would have much less reuse because of setting additional_args on the PexFromTargetsRequest.

[ci skip-rust]
[ci skip-build-wheels]

[stuhood]

In trying to fix that, I realized it is useful to simplify no longer having a requirements PEX vs. runner PEX. Originally, we split this so that the requirements PEX shared the cache between goals like test and lint. That is less relevant now that we first resolve from the constraints/lockfile, then extract the subset of deps - most of the heavy lifting will already be shared.

This isn't the default yet, but it probably can be once we have multiple user resolves?

[Eric-Arellano]

This isn't the default yet, but it probably can be once we have multiple user resolves?

It's the default if you have set up a constraints file, which we strongly recommend: https://www.pantsbuild.org/v2.8/docs/python-third-party-dependencies#using-a-lockfile-strongly-recommended