feat(component-failover-adoption): unify worker's dual connect paths into single pipeline

Replace worker's separate default/single-host and multi-candidate connect
branches with one path: synthesize-or-accept a candidate list, validate,
convert via xce_cluster_config_to_client_config(), connect once. Register
a flag-only rejoin callback (no I/O, no client-lib reentry) and remove the
liveness probe's bounded give-up so the library owns retry/recovery.

src/worker/testsuite/meson.build

@@ -0,0 +1,24 @@
+# Worker unit test suite (component-failover-adoption, task 2.1). White-box
+# tests #include the production .c file(s) under test directly (same pattern
+# as scheduler/testsuite's test_handlers.c etc.), so they link the same
+# dependency set the real xcecd/xcecd_worker executables use rather than a
+# subset of xcecd_srcs -- see test_controller_connector.c's header comment
+# for why controller_connector.c is not also listed in xcecd_srcs here (it
+# would double-define every symbol in that file).
+
+worker_test_incdir = include_directories('../include', '../../include', '.',
+                                         '../src', '../../lib')
+
+worker_test_deps = [xcecd_worker_deps, unity_dep]
+
+controller_connector_test = executable('controller_connector_test',
+                                       'test_controller_connector.c',
+                                       c_args: ['-DDBUS_MANAGER'],
+                                       include_directories: [worker_test_incdir],
+                                       dependencies: worker_test_deps,
+                                       install: false)
+
+test('worker controller_connector test', controller_connector_test,
+    suite: 'worker',
+    timeout: 60,
+    env: ['ASAN_OPTIONS=detect_leaks=0'])