Merge branch 'upgrade-newrelic-rpm' into 'master'

Upgrade newrelic_rpm from 3.14.1.311 to 3.16.0.318.

## What does this MR do?

While we intend to remove newrelic in the future, it'll probably not happen until 9.0 due to. In the meantime, I'd like to update the gem so it won't block Rails 5.

Changelog: https://github.com/newrelic/rpm/blob/master/CHANGELOG

## Why was this MR needed?

Rails 5 compatibility.

Relevant issues: #14286, #12860 

See merge request !5553

Gemfile

@@ -326,7 +326,7 @@ group :production do
   gem 'gitlab_meta', '7.0'
 end
 
-gem 'newrelic_rpm', '~> 3.14'
+gem 'newrelic_rpm', '~> 3.16'
 
 gem 'octokit', '~> 4.3.0'
 

Gemfile.lock

@@ -404,7 +404,7 @@ GEM
     nested_form (0.3.2)
     net-ldap (0.12.1)
     net-ssh (3.0.1)
-    newrelic_rpm (3.14.1.311)
+    newrelic_rpm (3.16.0.318)
     nokogiri (1.6.8)
       mini_portile2 (~> 2.1.0)
       pkg-config (~> 1.1.7)
@@ -902,7 +902,7 @@ DEPENDENCIES
   mysql2 (~> 0.3.16)
   nested_form (~> 0.3.2)
   net-ssh (~> 3.0.1)
-  newrelic_rpm (~> 3.14)
+  newrelic_rpm (~> 3.16)
   nokogiri (~> 1.6.7, >= 1.6.7.2)
   oauth2 (~> 1.2.0)
   octokit (~> 4.3.0)