Fix, DeviceCapabilityListener does not try to register IMS registration callback.

When IImsFeatureStatusCallback#notifyImsFeatureStatus() calls with unavailable and ready within short time, the PublishControllerImpl's handler calls DeviceCapabilityListener#onRcsConnected and #onRcsDisconnected consecutively.
During this time the DeviceCapabilityListener keeps EVENT_UNREGISTER_IMS_CHANGE and EVENT_REGISTER_IMS_CONTENT_CHANGE messages in Q. When the DeviceCapabilityListener handles EVENT_UNREGISTER_IMS_CHANGE message, it removes EVENT_REGISTER_IMS_CONTENT_CHANGE from Q.
By deleting EVENT_REGISTER_IMS_CONTENT_CHANGE, the DeviceCapabilityListener does not try to register the IMS registration callback.

Bug: 287833083
Test: atest DeviceCapabilityListenerTest, RcsUceAdapterTest
Test: AT&T and TMO live network
Merged-In: I5010adfb3e1ce2880cb8f816f021c44257d9c521
Change-Id: I5010adfb3e1ce2880cb8f816f021c44257d9c521