Use LC-X for topo db key

[congwang09]

This PR reverts part of #328, to use LC-X as database key. Because using domain name as db key caused some issues on provisioning connection.

[coveralls]

Pull Request Test Coverage Report for Build 11164979631

Details

• 0 of 7 (0.0%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.02%) to 58.374%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sdx_controller/handlers/lc_message_handler.py	0	2	0.0%
sdx_controller/messaging/rpc_queue_consumer.py	0	5	0.0%

Files with Coverage Reduction	New Missed Lines	%
sdx_controller/handlers/lc_message_handler.py	1	24.0%

Totals
Change from base Build 11131304124:	-0.02%
Covered Lines:	1086
Relevant Lines:	1918

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💛 - Coveralls

[YufengXin]

note: 1. domain_name = self.parse_helper.find_domain_name(msg_id, ":")
Now: LC-X: need to be deterministic for next PR