Increase Net::HTTP / rest-client open_timeout
Increase Net::HTTP / rest-client open_timeout

Starting with Ruby v2.3.0 the default value for `open_timeout` changed
from `nil` (disabled) to `60` seconds. This 60 second value remains in
current released versions of Ruby which is why we continue to see this
behavior in newer versions as well.

  https://github.com/ruby/ruby/commit/52e1c3b0ab41041f7f51a7afc3fce3aab97bc010

This caused periodic test failures which were observed and documented
when we originally moved from Ruby v2.2.6 to v2.3.3.

  https://github.com/chef/chef-server/commit/e7a2ac802f50b832c402f54e78881208d80ce6ad

More recently these timeouts have caused increase of erratic test
failures on both TravisCI and internal Jenkins build for slower
platforms. Rather than setting an `open_timeout` value of `nil` and
disabling the `open_timeout` entirely I have chosen to set a 300 second
timeout as a starting point for increasing the timeout value to allow
for legitimate timeouts to occur rather than having test jobs get
stuck indefinitely.

Signed-off-by: Ryan Hass <7a1efea0847aa10fda44596a4a622bd3187d968e@users.noreply.github.com>

chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server