Remove `PendingInbound` status for CCTX

[lumtis]

Describe the Issue This status is unnecessary, it is used when the CCTX is initialize but the outcome of a message creating a CCTX always end up with a initiated outbound. This status only exist during the execution of the message but never for created CCTX that can be queried.

For the sake of simplification we should remove this status.

A CCTX is created when a inbound is validated and the initial status of a CCTX is always PendingOutbound (external destination chain) or OutboundMined|PendingRevert (ZetaChain destination)