Remove vendored submodule from libdbus-sys #1879

Job	Run time
checks_with_udev (RUST_LOG=stratisd=debug make -f Makefile test-loop, 1.73.0, cargo)	14m 23s
checks (make -f Makefile clippy, 1.73.0, clippy)	5m 6s
checks (PROFILEDIR=debug make -f Makefile build, 1.73.0, cargo)	3m 46s
checks (PROFILEDIR=debug make -f Makefile build-min, 1.73.0, cargo)	2m 43s
checks (PROFILEDIR=debug make -f Makefile build-no-ipc, 1.73.0, cargo)	2m 30s
checks (PROFILEDIR=debug make -f Makefile stratis-dumpmetadata, 1.73.0, cargo)	2m 54s
checks (make -f Makefile docs-ci, 1.73.0, cargo)	2m 13s
checks (make -f Makefile test, 1.73.0, cargo)	3m 55s
checks (TANG_URL=localhost make -f Makefile test-clevis-loop-should-fail, 1.73.0, cargo)	3m 15s
checks (make -f Makefile build, 1.73.0, cargo)	4m 28s
checks (make -f Makefile build-min, 1.73.0, cargo)	4m 38s
checks (make -f Makefile build-no-ipc, 1.73.0, cargo)	3m 56s
	53m 47s

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