CI: adjust UL throughput target for 2x2 RFSim5G test on acamas

This commit reduces the UL throughput target in the 2x2 test to align
with the host’s performance capabilities. The adjustment ensures more
reliable and consistent CI results.

ci-scripts/xml_files/container_5g_rfsim_2x2.xml

@@ -112,8 +112,8 @@
 
         <testCase id="030002">
                 <class>Iperf</class>
-                <desc>Iperf (UL/4Mbps/UDP)(30 sec)</desc>
-                <iperf_args>-u -b 4M -t 20</iperf_args>
+                <desc>Iperf (UL/3Mbps/UDP)(30 sec)</desc>
+                <iperf_args>-u -b 3M -t 20</iperf_args>
                 <id>rfsim5g_ue</id>
                 <nodes>acamas</nodes>
                 <svr_id>rfsim5g_ext_dn</svr_id>