fix: wrap props in deriveds more conservatively in legacy mode

[Rich-Harris]

See #11548 (comment). This fixes #11448 by wrapping props in deriveds in legacy mode, unless they're trivial

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[dummdidumm]

Is this the right or wrong angle? I.e. should a parent component be the one to decide how the child component receives prop updates, or should it be the child component? I.e. if a runes component uses a legacy component, should the legacy component be the one saying "I only update on an object prop change"? I'm unsure.
Granted, this way around is easier to implement.

[Rich-Harris]

Ah yeah, you're right. I had a crack at implementing it that way round in #11574 but there's a failing test that I cannot for the life of me get to the bottom of

[Rich-Harris]

closing in favour of #11577