[FAB-12912] Fix raft consenter.go linter warnings
[FAB-12912] Fix raft consenter.go linter warnings

Address linter errors and fix bug where check of error result while
reading metadata was omitted.

Change-Id: I1bf87c6da5273c26916ca735b32ae0b7dd4bad8c
Signed-off-by: Artem Barger <6d127d713cb520aa658cf81ac2373d74ffc1958c@il.ibm.com>

hyperledger/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric,muralisrini/fabric,binhn/fabric,stemlending/fabric,jimthematrix/fabric,stemlending/fabric,stemlending/fabric,manish-sethi/fabric-sidedb,stemlending/fabric,manish-sethi/fabric,manish-sethi/fabric-sidedb,xixuejia/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,hyperledger/fabric,xixuejia/fabric,xixuejia/fabric,muralisrini/fabric,jimthematrix/fabric,binhn/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,muralisrini/fabric,binhn/fabric