re-enable dependabot with 14-day cooldown

Rename .disabled configs back and add cooldown: default-days: 14

Signed-off-by: Moe Zein <moe.zein@datadoghq.com>

Author: moezein0

.github/dependabot.yml

@@ -0,0 +1,12 @@
+version: 2
+updates:
+- package-ecosystem: github-actions
+  directory: /
+  schedule:
+    interval: weekly
+  groups:
+    gh-actions-packages:
+      patterns:
+      - '*'
+  cooldown:
+    default-days: 14