Cleanup topology handling logic

[congwang09]

We used to use LC-1,2,3 to represent the LCs, to be easier to loop through the topologies from db when SDX starts up. Now we have the list of LC domain names saved in db, so we don't need the LC counter any more. This can simplify the logic for handling topologies.

[coveralls]

Pull Request Test Coverage Report for Build 11575603928

Details

• 1 of 19 (5.26%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 56.886%

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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	1	17	5.88%

Files with Coverage Reduction	New Missed Lines	%
sdx_controller/handlers/lc_message_handler.py	2	30.0%

Totals
Change from base Build 11524951004:	0.1%
Covered Lines:	1107
Relevant Lines:	1946

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💛 - Coveralls