Remove a leftover from CMQs

Author: lhoguin

deps/rabbit_common/src/rabbit_registry.erl

@@ -189,7 +189,6 @@ class_module(queue_decorator)     -> rabbit_queue_decorator;
 class_module(policy_validator)    -> rabbit_policy_validator;
 class_module(operator_policy_validator) -> rabbit_policy_validator;
 class_module(policy_merge_strategy)     -> rabbit_policy_merge_strategy;
-class_module(ha_mode)                   -> rabbit_mirror_queue_mode;
 class_module(channel_interceptor)       -> rabbit_channel_interceptor.
 
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