ASEC-131:Remove reference to SDG as the team no longer exists (#168)

Author: dmellonielet

.github/PULL_REQUEST_TEMPLATE.md

@@ -15,10 +15,4 @@ If this change cannot be feasibly tested, please explain why,
 unless the change does not modify code (e.g. only modifies docs, comments).
 -->
 
-**For Datadog employees**:
-- [ ] If this PR touches code that signs or publishes builds or packages, or handles
-credentials of any kind, I've requested a review from `@DataDog/security-design-and-guidance`.
-- [ ] This PR doesn't touch any of that.
-
-Unsure? Have a question? Request a review!