chore: add SQL tests for FIRST/LAST aggregates (#3891)

Author: comphead

docs/source/user-guide/latest/compatibility.md

@@ -89,8 +89,6 @@ the [Comet Supported Expressions Guide](expressions.md) for more information on
 
 - **Corr**: Returns null instead of NaN in some edge cases.
   [#2646](https://github.com/apache/datafusion-comet/issues/2646)
-- **First, Last**: These functions are not deterministic. When `ignoreNulls` is set, results may not match Spark.
-  [#1630](https://github.com/apache/datafusion-comet/issues/1630)
 
 ### Struct Expressions