[config] Add incremental_settings.json

This file is a placeholder which makes it possible to exercise the full
create_branch.py workflow with modifications to the
incremental_settings.json file, mimicking the file which exists in the
real integration.git.

Bug: 86879
Change-Id: I5185ceaddf4c92588e918563f1383ef8b28e85ec
Reviewed-on: https://fuchsia-review.googlesource.com/c/infra/roller-tests/integration/+/608621
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
Fuchsia-Auto-Submit: Anthony Fandrianto <atyfto@google.com>
Reviewed-by: Oliver Newman <olivernewman@google.com>
diff --git a/infra/config/common/incremental_settings.json b/infra/config/common/incremental_settings.json
new file mode 100644
index 0000000..ba9418f
--- /dev/null
+++ b/infra/config/common/incremental_settings.json
@@ -0,0 +1,3 @@
+{
+	"disabled": false
+}
\ No newline at end of file