northd: Autodiscover centralize_routing. #4680

Job	Run time
linux rpm fedora	8m 33s
osx clang --disable-ssl	1m 53s
Prepare container	3m 40s
linux gcc --disable-ssl	2m 43s
linux clang --disable-ssl	2m 46s
linux gcc test -300	9m 25s
linux gcc test 301-600	6m 36s
linux gcc test 601- unstable	7m 4s
linux clang test sanitizers -300	12m 41s
linux clang test sanitizers 301-600	9m 12s
linux clang test sanitizers 601- unstable	9m 9s
linux gcc test -ljemalloc -300	9m 43s
linux gcc test -ljemalloc 301-600	6m 50s
linux gcc test -ljemalloc 601- unstable	7m 11s
linux gcc system-test-dpdk dpdk -100	17m 8s
linux gcc system-test-dpdk dpdk 101- unstable	14m 45s
linux gcc system-test-userspace -100	16m 19s
linux gcc system-test-userspace 101- unstable	13m 27s
linux gcc system-test -100	18m 40s
linux gcc system-test 101- unstable	17m 23s
linux clang system-test sanitizers -100	20m 34s
linux clang system-test sanitizers 101- unstable	19m 18s
linux x86 gcc --disable-ssl	2m 46s
	3h 57m 46s

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