[automerger] Init gain config to prevent uninit leak. am: ebe0777e am:...

[automerger] Init gain config to prevent uninit leak. am: ebe0777e am: 1f39e79a am: f57d4e10 am: 3fc94f3a am: e279da40 am: 7a41b25c am: 3c5a6f06

Change-Id: I3d0c843a2b28b15236858bfab1a8bf192a121f00