Changes made to the build/install commands of a pinned non-dune package are not picked up until `dune pkg lock` is run

[gridbugs]

Normally users can change files in the source of a pinned package and expect the changes to be visible to the current project (which pins said package), though currently running dune clean is necessary (see https://github.com/ocaml/dune/issues/10232). This enables the workflow of testing local changes to a library by cloning one of its reverse dependencies and pinning the local source of the library.

However, if the build/install commands in the pinned package's opam file are changed, the changes are not visible to the current project until dune pkg lock is run.

Repro: see test added in https://github.com/ocaml/dune/pull/10235

This happens because the build/install commands from the pinned package are copied to the lockdir during dune pkg lock and are subsequently used by dune to build the pinned package. One way to avoid this issue would be deferring parsing the build/install commands of the pinned package until dune attempts to build the package.