fix: properly handling timeout when revoking ETCD lease

[reinaldooli]

This is a cherrypick from the changes made here.
Since pitaya v3 still using ETCD, these changes needs to be propagated.

[coveralls]

Pull Request Test Coverage Report for Build 10457228137

Details

• 0 of 12 (0.0%) changed or added relevant lines in 1 file are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 59.164%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/cluster/etcd_service_discovery.go	0	12	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/modules/binary.go	4	69.57%

Totals
Change from base Build 10368957457:	-0.04%
Covered Lines:	4900
Relevant Lines:	8282

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💛 - Coveralls