Remove deprecated `Expr::Wildcard` variant

[alamb]

Is your feature request related to a problem or challenge?

The API health policy deprecation guidelines say deprecated APIs remain for

6 major versions or 6 months, whichever is longer

main is at 55.0.0, so the next release is 56.0.0 and anything deprecated in 50.0.0 or earlier can now be removed.

Item	Deprecated in	Replacement
Expr::Wildcard	46.0.0	resolve to concrete columns when building the LogicalPlan

Describe the solution you'd like

Remove the Expr::Wildcard variant and supporting code

This one is larger than the other removals in this sweep, so it is not a good first issue:

• There are ~75 Expr::Wildcard references across ~26 files (expr, sql, optimizer, proto, functions-aggregate, functions-window, catalog-listing, substrait)
• Removing an enum variant breaks downstream match arms even when they never construct a wildcard
• There is a corresponding Wildcard message in datafusion.proto, so the serialization surface needs a decision too

Notes:

• While this is a breaking Rust API change, the PR should carry the api change label
• Unlike the other removals in this sweep, this one is probably worth a note in the 56.0.0 upgrade guide, since downstream match arms break without a direct compiler-suggested replacement

Describe alternatives you've considered

N/A

Additional context

Supersedes #7765, which tracked the same removal.

Follow on to #23080, which did the same sweep at the 49.0.0 cutoff, and #24535.

[vvvdwbvvv]

take