fix(glue): Exclude historical schemas from Glue columns

[VABVAT]

Which issue does this PR close?

• Closes iceberg-catalog-glue pushes all historical schema fields to Glue, causing duplicate columns in Glue UI #2749

What changes are included in this PR?

This PR updates Glue schema conversion so AWS Glue StorageDescriptor.columns is populated only from the current Iceberg schema.

Previously, GlueSchemaBuilder::from_iceberg converted the current schema and then also converted historical schemas from table metadata. Those historical fields were written to Glue with iceberg.field.current=false, but Glue does not use that parameter to filter visible columns, which could cause duplicate columns to appear in the Glue Console after schema evolution.

Historical schemas are still preserved in Iceberg table metadata. This change only prevents them from being projected into Glue's visible column list.

Are these changes tested?

Yes.

Added a regression test covering schema evolution with historical schemas, and verified the Glue schema output contains only current schema fields.

Ran locally:

cargo test -p iceberg-catalog-glue

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[David-Banquet]

Thanks for picking this up again.

This drops the older schemas entirely, so columns removed from the table also disappear from Glue. The Java catalog keeps them: toColumns in IcebergToGlueConverter writes the current schema first, then the older schemas with iceberg.field.current=false, and skips any name it has already added. The duplicates come from that missing name check, so keeping the loop and adding a HashSet of top-level names already written would fix #2749 and keep the Glue output the same as Java's. A table written by both Spark and iceberg-rust would otherwise see its Glue columns change depending on which engine committed last.

If the maintainers prefer current-schema-only, that's a fair choice too, but it's a behavior change from Java and probably worth saying so in the PR description.

Two smaller things:

• The new test only adds a column, where both approaches give the same result. A case that drops a column (and one where a field keeps its name across schemas with a different type) would show which behavior is intended.
• builder.is_current = false; and its comment can go: the fields are private and nothing reads them after from_iceberg returns.