MM-23568: Add rudder to server diagnostics. (#14151)

* MM-23568: Add rudder to server diagnostics.

* Add unit test.

* Go mod tidy.

* CSP Header fix.

* Fix review comments.

* Update web/handlers.go

Co-Authored-By: Jesse Hallam <jesse.hallam@gmail.com>

* Partially address review comments.

* fix tests.

* Finish implementing review suggestions and then fixing tests.

* Fix CSP Header tests.

Co-authored-by: Jesse Hallam <jesse.hallam@gmail.com>

go.mod

@@ -72,7 +72,8 @@ require (
 	github.com/prometheus/client_golang v1.4.0
 	github.com/prometheus/client_model v0.2.0 // indirect
 	github.com/rs/cors v1.7.0
-	github.com/russellhaering/goxmldsig v0.0.0-20180430223755-7acd5e4a6ef7 // indirect
+	github.com/rudderlabs/analytics-go v3.1.0+incompatible
+	github.com/russellhaering/goxmldsig v0.0.0-20180430223755-7acd5e4a6ef7
 	github.com/rwcarlsen/goexif v0.0.0-20190401172101-9e8deecbddbd
 	github.com/segmentio/analytics-go v3.1.0+incompatible
 	github.com/segmentio/backo-go v0.0.0-20160424052352-204274ad699c // indirect