Add telegraf ping plugin

Add template for telegraf ping plugin
Add meta for ping confguration
Add NodeDown alert

Change-Id: I8ed64eca9eaeca45e4526528e9bcab795131d914
PROD-related: PROD-27580 (PROD:27580)
(cherry picked from commit 754ebbfbea65329012c1c8bc05772ad22985c59c)
diff --git a/metadata/service/support.yml b/metadata/service/support.yml
index 21ff9f2..213c3a1 100644
--- a/metadata/service/support.yml
+++ b/metadata/service/support.yml
@@ -5,4 +5,6 @@
         enabled: true
       prometheus:
         enabled: true
+      telegraf:
+        enabled: true