Bluetooth: Host: Add log entry for connection creation timeout

This makes it more clear what is happening when the host cancels
connection creation where the controller raises
the connection complete event with status set to
"UNKNOWN CONNECTION IDENTIFIER (0x02)".

This is especially useful for developers not familiar with this
detail in the spec.

See also: Core_v5.4, Vol 4, Part E, Section 7.8.13,
LE Create Connection Cancel command.

Signed-off-by: Rubin Gerritsen <rubin.gerritsen@nordicsemi.no>