Revert "[WFLY-3362] make sure operations get cancelled on channel close"

This reverts commit 89d132d5376f9706aefd34f6eee2bddfb4e83ce6.

Commit introduces a race on the client side during operations like reload/shutdown that result in the channel closing.
Merge pull request #6308 from bstansberry/revert-3362

Revert "[WFLY-3362] make sure operations get cancelled on channel close"
[WFLY-2741] Single process management operation timeouts
Use shared utility for managing test extension module
[WFLY-3058] Expose actively executing mgmt ops as management resources
[WFLY-3090] Prevent mgmt op cancellation resulting in closing intra-process connections
[WFLY-3091] Fix propagation of mgmt op cancellation to server update tasks
Tests of the above and of WFLY-3058
[WFLY-3058] Add convenience ops to find/cancel non-progressing ops
[WFLY-3381] Handle race between HC's cancel of an op and the original op