Add sendemail connection timeout and increase threads to 2

By default there is no timeout, because we are using external smtp
service connection can hang on sending the email and block the
operation.

By default sendemail threadpool is set to 1, because we are using
external smtp service connection can be slow, having one thread can slow
down the operation.

Change-Id: Id06f161448bae14437f9123cfd3a6dd199ee6015
diff --git a/gerrit/etc/gerrit.config.template b/gerrit/etc/gerrit.config.template
index c283e5a..7a84673 100644
--- a/gerrit/etc/gerrit.config.template
+++ b/gerrit/etc/gerrit.config.template
@@ -27,6 +27,8 @@
 
 [sendemail]
   smtpServer = {{ SMTP_SERVER  }}
+  connectTimeout = 30 s
+  threadPoolSize = 2
   smtpEncryption = ssl
   sslVerify = false
   smtpUser = {{ SMTP_USER }}