Disable connection reaping for MySQL

On GitLab Cloud, MySQL connection reaping seemed to cause more problems
(exceptions and segfaults in the native MySQL client) than it solved.

CHANGELOG

@@ -9,6 +9,7 @@ v 6.8.0
   - Changed permission of gitlab-satellites directory not to be world accessible
   - Protected branch does not allow force push
   - Fix popen bug in `rake gitlab:satellites:create`
+  - Disable connection reaping for MySQL
 v 6.7.3
   - Fix the merge notification email not being sent (Pierre de La Morinerie)

config/database.yml.mysql

@@ -7,7 +7,6 @@ production:
   reconnect: false
   database: gitlabhq_production
   pool: 10
-  reaping_frequency: 10
   username: git
   password: "secure password"
   # host: localhost