Fix microbatch behavior flag check

Previously we were adding `microbatch` to the list of `builtin_incremental_strategies`
only when the behavior flag `require_batched_execution_for_custom_microbatch_strategy`
was set to True. However in reality, we only want to set it True when that flag evaluates
to False. This is because having the flag set to True implies by the transitive property
that the project has a custom microbatch macro defined. In this situation, we _don't_ want
`microbatch` to be in the list of `builtins` because if the adapter doesn't have a builtin
`microbatch` macro, things will break. Said another way, the only time that having `microbatch`
in the list of builtin incremental strategies is relevant is when the flag is False.

.changes/unreleased/Fixes-20241112-141109.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: Negate the check for microbatch behavior flag in determining builtins
+time: 2024-11-12T14:11:09.341634-06:00
+custom:
+  Author: QMalcolm
+  Issue: 349

dbt/adapters/base/impl.py

@@ -1579,7 +1579,7 @@ def valid_incremental_strategies(self):
 
     def builtin_incremental_strategies(self):
         builtin_strategies = ["append", "delete+insert", "merge", "insert_overwrite"]
-        if self.behavior.require_batched_execution_for_custom_microbatch_strategy.no_warn:
+        if not self.behavior.require_batched_execution_for_custom_microbatch_strategy.no_warn:
             builtin_strategies.append("microbatch")
 
         return builtin_strategies