Remove all the Interface Bridge settings, disconnect the cables from the ports. Then try to enter this template:
interface bridge 2
interface GigabitEthernet1/0/19
port link-aggregation group 2
interface GigabitEthernet1/0/20
port link-aggregation group 2
interface bridge 2
description CEntOS_Server
port link-mode bridge
Re-connect the cables and watch if the bridge-interface is up. Use the display link-aggregation verbose to check the aggregation group status. Make a double check in the server settings, some servers uses the LACP to bind interfaces. If this is necessary you will need to enable LACP in the bridge-interface too, using the command link-aggregation mode dynamic.
A few days ago I faced a similar problem; when I tried to set up the LAG in this way the aggregated link started to work. This occurs because the Bridge-aggregation interface acts as the main interface, reflecting all the settings in the selected ports of its link-aggregation group.
If you enter any command straight in the ports, not in the virtual bridge-aggregation port, the communication goes down. This is a particularity of v.5 software, that in this features acts as the Etherchannel (interface port-channel) in Cisco switches.
HTH.