[Refactor] use new model.batch context vars (#1258)

Author: MichelleArk

.changes/unreleased/Under the Hood-20241205-144036.yaml

@@ -0,0 +1,6 @@
+kind: Under the Hood
+body: Use new `batch` context variables over `node.config.__dbt_internal` ones
+time: 2024-12-05T14:40:36.373637-05:00
+custom:
+  Author: michelleark
+  Issue: "1263"

dbt/include/snowflake/macros/materializations/merge.sql

@@ -57,10 +57,10 @@
     {%- set incremental_predicates = [] if arg_dict.get('incremental_predicates') is none else arg_dict.get('incremental_predicates') -%}
 
     {#-- Add additional incremental_predicates to filter for batch --#}
-    {% if model.config.get("__dbt_internal_microbatch_event_time_start") -%}
+    {% if model.batch and model.batch.event_time_start -%}
         {% do incremental_predicates.append("DBT_INTERNAL_TARGET." ~ model.config.event_time ~ " >= to_timestamp_tz('" ~ model.config.__dbt_internal_microbatch_event_time_start ~ "')") %}
     {% endif %}
-    {% if model.config.__dbt_internal_microbatch_event_time_end -%}
+    {% if model.batch and model.batch.event_time_end -%}
         {% do incremental_predicates.append("DBT_INTERNAL_TARGET." ~ model.config.event_time ~ " < to_timestamp_tz('" ~ model.config.__dbt_internal_microbatch_event_time_end ~ "')") %}
     {% endif %}
     {% do arg_dict.update({'incremental_predicates': incremental_predicates}) %}