refactor: 8771 simplifications without 8781 import reforms

[erights]

closes: #XXXX
refs: #8771 #8781

Description

#8771 is staged on #8781 , under the assumption that #8781 would be merged first. But they're mostly independent. In case the changes from #8771 should get merged first, this PR adds to those changes another small commit to compensate for the absence of #8781.

Security Considerations

Scaling Considerations

Documentation Considerations

Testing Considerations

Upgrade Considerations

[turadg]

#8771 is staged on #8781 , under the assumption that #8781 would be merged first. But they're mostly independent

I don't see it staged. The base branch is master. It's passing checks so it is indeed independent.

However the fix: compensate for lack of 8781 prevent this from being merged as is. For one, the conventional commits show up in the changelog and commit is irrelevant to any consumer of the package. There's nothing being fixed that has been released. It's "fixing up" the refactor commit to make it work, which should just be part of the refactor commit.

Separately, the removal of the same-structure package is not itself a refactor. Basically we're freezing the NPM-published @agoric/same-structure because it won't ever be published again. As part of landing this, someone should deprecate the published package.

[erights]

Closed in favor of #8771