avro: restore compatibility docs and sqllogictest expectations

Author: getChan

datafusion/sqllogictest/test_files/avro.slt

@@ -124,7 +124,7 @@ LOCATION '../../testing/data/avro/alltypes_plain.avro';
 
 statement ok
 CREATE EXTERNAL TABLE single_nan (
-  mycol DOUBLE
+  mycol FLOAT
 )
 STORED AS AVRO
 LOCATION '../../testing/data/avro/single_nan.avro';

docs/source/library-user-guide/upgrading/53.0.0.md

@@ -473,11 +473,11 @@ Now:
 0 row(s) fetched.
 ```
 
-### Avro API, feature, and decoding changes
+### Avro API, feature, and timestamp decoding changes
 
 As part of the Avro reader migration (see [#17861]), DataFusion now delegates
-Avro-to-Arrow type decoding to `arrow-avro` (aligned with `arrow-avro` semantics),
-and several Avro-related APIs/feature wiring changed:
+Avro-to-Arrow type decoding to `arrow-avro`, and several Avro-related
+APIs/feature wiring changed:
 
 - `DataFusionError::AvroError` has been removed.
 - `From<apache_avro::Error> for DataFusionError` has been removed.
@@ -487,8 +487,7 @@ and several Avro-related APIs/feature wiring changed:
 - Cargo feature wiring changed:
   - `datafusion` crate `avro` feature no longer enables `datafusion-common/avro`
   - `datafusion-proto` crate `avro` feature no longer enables `datafusion-common/avro`
-- **Avro datatype interpretation now follows `arrow-avro` behavior.** Notable effects:
-  - Avro `string` logical values are read as Arrow `Binary` in DataFusion Avro scans
+- **Avro timestamp logical type interpretation changed.** Notable effects:
   - Avro `timestamp-*` logical types are read as UTC timezone-aware Arrow timestamps
     (`Timestamp(..., Some("+00:00"))`)
   - Avro `local-timestamp-*` logical types remain timezone-naive
@@ -499,8 +498,7 @@ and several Avro-related APIs/feature wiring changed:
 - Users matching on `DataFusionError::AvroError`
 - Users importing `datafusion::apache_avro`
 - Users depending on the old `datafusion-common/avro` feature wiring
-- Users relying on DataFusion-specific Avro decoding behavior (especially `string`
-  and timestamp logical types)
+- Users relying on previous Avro timestamp logical type behavior
 
 **Migration guide:**
 
@@ -509,8 +507,6 @@ and several Avro-related APIs/feature wiring changed:
   the current error surface.
 - If you depend on Avro feature propagation, update Cargo feature expectations:
   `datafusion`/`datafusion-proto` `avro` no longer enables `datafusion-common/avro`.
-- Review Avro table schemas and add explicit casts where needed for binary-backed
-  string values (for example, `CAST(binary_col AS VARCHAR)`).
 - Validate timestamp handling where timezone semantics matter:
   `timestamp-*` is UTC timezone-aware, while `local-timestamp-*` is timezone-naive.