Related tests already existed for STP_Tests_M3UA, but we want to explicitly test against M3UA_TCP since these tests involve the transport layer directly.
stp: m3ua: Fix incorrect RCTX being sent in TC_combinedlset_loadshare
An ASPAC was being sent containing an RCTX of an unrelated AS to the sending ASP. Newer libosmo-sigtran properly validates AS/RCTX is associated to the ASP in the local config, and hence now returns an error properly making the test fail.
