Fix external issue tracker hook/test for HTTPS URLs

If HTTPS was used for 'project_url', an error was raised because a HTTP
connection was established to the default HTTPS port.

The code has been corrected and simplified by using HTTParty.
Additionally, the request now is made directly to the 'project_url'
instead of the extracted root path.

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 v 7.12.0 (unreleased)
+  - Fix external issue tracker hook/test for HTTPS URLs (Daniel Gerhardt)
   - Don't notify users mentioned in code blocks or blockquotes.
   - Omit link to generate labels if user does not have access to create them (Stan Hu)
   - Disable changing of the source branch in merge request update API (Stan Hu)

app/models/project_services/issue_tracker_service.rb

@@ -81,18 +81,13 @@ class IssueTrackerService < Service
     result = false
     begin
-      url = URI.parse(self.project_url)
-      if url.host && url.port
-        http = Net::HTTP.start(url.host, url.port, { open_timeout: 5, read_timeout: 5 })
-        response = http.head("/")
-
-        if response
-          message = "#{self.type} received response #{response.code} when attempting to connect to #{self.project_url}"
-          result = true
-        end
+      response = HTTParty.head(self.project_url, verify: true)
+      if response
+        message = "#{self.type} received response #{response.code} when attempting to connect to #{self.project_url}"
+        result = true
       end
-    rescue Timeout::Error, SocketError, Errno::ECONNRESET, Errno::ECONNREFUSED => error
+    rescue HTTParty::Error, Timeout::Error, SocketError, Errno::ECONNRESET, Errno::ECONNREFUSED => error
       message = "#{self.type} had an error when trying to connect to #{self.project_url}: #{error.message}"
     end
     Rails.logger.info(message)