fix: incorrect storage descriptor when creating tables in GlueCatalog

[geruh]

Which issue does this PR close?

Fixes two bugs in the GlueCatalogs table creation that caused inconsistency with Iceberg core and PyIceberg implementations:

• StorageDescriptor.Location incorrectly set to metadata file path instead of table base location
• iceberg.field.optional parameter logic inverted - was setting it to field.required instead of !field.required

Iceberg ref:

• location: https://github.com/apache/iceberg/blob/main/aws/src/main/java/org/apache/iceberg/aws/glue/IcebergToGlueConverter.java#L280
• field.optional: https://github.com/apache/iceberg/blob/main/aws/src/main/java/org/apache/iceberg/aws/glue/IcebergToGlueConverter.java#L377

What changes are included in this PR?

Location

Before:

{
  "StorageDescriptor": {
    "Location": "s3://bucket/table/metadata/00000-uuid.metadata.json"
  },
  "Parameters": {
    "metadata_location": "s3://bucket/table/metadata/00000-uuid.metadata.json"
  }
}

After:

{
  "StorageDescriptor": {
    "Location": "s3://bucket/table"
  },
  "Parameters": {
    "metadata_location": "s3://bucket/table/metadata/00000-uuid.metadata.json"
  }
}

Schema (with required field)

Rust Schema

 NestedField::required(1, "foo", Type::Primitive(PrimitiveType::String)).into(),

Before:

{
    "Name": "foo",
    "Type": "string",
    "Parameters": {
        "iceberg.field.current": "true",
        "iceberg.field.id": "2",
        "iceberg.field.optional": "true" <---
    }
}

After:

{
    "Name": "foo",
    "Type": "string",
    "Parameters": {
        "iceberg.field.current": "true",
        "iceberg.field.id": "2",
        "iceberg.field.optional": "false" <---
    }
}

Are these changes tested?

• Repaired the existing test
• Tested manually with GlueCatalog.

[Xuanwo]

Thank you!