detect: avoids case of useless detection on txs

detect: avoids case of useless detection on txs

When a TCP flow packet has not led to app-layer updates,
it is useless to run DetectRunTx, as there cannot be new
matches.

This happens for instance, when one side sends in a row multiple
packets which are not acked (and thus not parsed in IDS mode).

Doing so requires to move up the call to
AppLayerParserSetTransactionInspectId
so that it is run the same times DetectRunTx is run, and not in the
case where the transaction was not updated.

Ticket: 6299