Set Jinja2's keep_trailing_newline=True in template_from_string.

Without this setting, the newline idempotence of scalar strings changes depending on whether
or not they contain any Jinja2 template blocks.

test/integration/roles/test_template/tasks/main.yml

@@ -63,4 +63,10 @@
   assert: 
     that: 
       - "file_result.changed != True"
-        
+
+# VERIFY STRING TEMPLATE PRESERVES NEWLINE
+
+- name: ensure template strings preserve newline
+  assert:
+    that:
+      - "newline_no_template_string == newline_template_string"

test/integration/roles/test_template/vars/main.yml

@@ -1 +1,3 @@
 templated_var: templated_var_loaded
+newline_template_string: "Hello {{ 'World' }}\n"
+newline_no_template_string: "Hello World\n"