[ty] Omit redundant definition inference owner keys (#25837)
## Summary
`DefinitionTypes` stores the queried definition key alongside common
single-binding and single-declaration results, even though that key is
always the Salsa query input.
This omits the redundant key from those inline variants and threads the
owner through iteration and cycle normalization so callers can
reconstruct it. Results for other definitions continue using the
existing boxed fallback.
Based on the measured shape counts, this is expected to reduce retained
memory by about 249 MB (0.25%) on the representative workload.
