Fixing neutron::server deprecated warnings

Clearing default values for deprecated reconnect_interval,
sql_idle_timeout, and sql_max_retries parameters.

Change-Id: I4b34e47dc9a814c0fbcc0fd6d8fe6033081a51d0
Closes-Bug: #1269623
(cherry picked from commit b14cee10c155c30dbf7b1645dfa095c4d5b0aa73)
Merge "Fixing neutron::server deprecated warnings" into stable/havana