Revert "fix: merge predicate for concurrent writes"

[Blajda]

reverts #2291

Introduces a regression to merge that occurred before #2158

Causes the following test to fail

async fn test_merge_pushdowns() {
    //See #2158
    let schema = vec![
        StructField::new(
            "id".to_string(),
            DataType::Primitive(PrimitiveType::String),
            true,
        ),
        StructField::new(
            "cost".to_string(),
            DataType::Primitive(PrimitiveType::Float),
            true,
        ),
        StructField::new(
            "month".to_string(),
            DataType::Primitive(PrimitiveType::String),
            true,
        ),
    ];

    let arrow_schema = Arc::new(ArrowSchema::new(vec![
        Field::new("id", ArrowDataType::Utf8, true),
        Field::new("cost", ArrowDataType::Float32, true),
        Field::new("month", ArrowDataType::Utf8, true),
    ]));

    let table = DeltaOps::new_in_memory()
        .create()
        .with_columns(schema)
        .await
        .unwrap();

    let ctx = SessionContext::new();
    let batch = RecordBatch::try_new(
        Arc::clone(&arrow_schema.clone()),
        vec![
            Arc::new(arrow::array::StringArray::from(vec!["A", "B"])),
            Arc::new(arrow::array::Float32Array::from(vec![Some(10.15), None])),
            Arc::new(arrow::array::StringArray::from(vec![
                "2023-07-04",
                "2023-07-04",
            ])),
        ],
    )
    .unwrap();

    let table = DeltaOps(table)
        .write(vec![batch.clone()])
        .with_save_mode(SaveMode::Append)
        .await
        .unwrap();
    assert_eq!(table.version(), 1);
    assert_eq!(table.get_files_count(), 1);

    let batch = RecordBatch::try_new(
        Arc::clone(&arrow_schema.clone()),
        vec![
            Arc::new(arrow::array::StringArray::from(vec!["A", "B"])),
            Arc::new(arrow::array::Float32Array::from(vec![Some(12.15), Some(11.15)])),
            Arc::new(arrow::array::StringArray::from(vec![
                "2023-07-04",
                "2023-07-04",
            ])),
        ],
    ).unwrap();
    let source = ctx.read_batch(batch).unwrap();

    let (table, _metrics) = DeltaOps(table)
        .merge(source, "target.id = source.id and target.cost is null")
        .with_source_alias("source")
        .with_target_alias("target")
        .when_matched_update(|insert| {
            insert
                .update("id", "target.id")
                .update("cost", "source.cost")
                .update("month", "target.month")
        })
        .unwrap()
        .await
        .unwrap();

    let expected = vec![
"+----+-------+------------+",
"| id | cost  | month      |",
"+----+-------+------------+",
"| A  | 10.15 | 2023-07-04 |",
"| B  | 11.15 | 2023-07-04 |",
"+----+-------+------------+",
    ];
    let actual = get_data(&table).await;
    assert_batches_sorted_eq!(&expected, &actual);
}

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