Avoid creating constructors where not warranted

[som-snytt]

Avoid creating constructors where not warranted.

Fixes #15144

[sjrd]

Looks good, but the "pre-tweaking" commit does not seem to have anything to do with the real commit of this PR. It should go in a separate refactoring-only PR.

[som-snytt]

That is literally why it's in a separate commit. It's in this PR because I had to clean up while wandering around the site, i.e., so-called "scouting".

Maybe there is a better term than "scouting" or "pre-tweaking", such as "twerking", since all twerking is pre-twerking by definition.

Edit: I don't know what to call the post-twerk at scala/scala#11059

[sjrd]

OK, sure.

FTR I disagree. IMO a separate commit is the least we can do of course, but I would only bundle it in a PR if the changes of that commit support the real commit afterwards (typically because there are colliding affected lines), but not if it's totally unrelated.

Approving not to delay this for no strong reason.