CI: refactor iperf3 UDP analysis function

- Add helper function to normalize bitrate values to Mbps for calculations.
- Add helper function to extract data from iperf test report.
- Clean up the UDP analysis function, improve test report formatting.
- Fix an issue where Gbps values were incorrectly reported due to inconsistent
  unit parsing.
- Update CI unit test report checks to match the new formatting.

ci-scripts/tests/log/iperf_udp_msg_nok.txt

@@ -1,4 +1,4 @@
-Sender Bitrate  : 0.52  Mbps
-Receiver Bitrate: 0.52  Mbps (too low! < 99%)
+Sender Bitrate  : 524.00 Kbps
+Receiver Bitrate: 524.00 Kbps (52.40%) (too low! < 99%)
 Jitter          : 0.026 ms
-Packet Loss     : 10 % (too high! > 0%)
+Packet Loss     : 10% (too high! > 0%)

ci-scripts/tests/log/iperf_udp_msg_nok2.txt

@@ -1,4 +1,4 @@
-Sender Bitrate  : 0.00  Mbps
-Receiver Bitrate: 3.98  Mbps (too low! < 99%)
+Sender Bitrate  : 0.00 bps
+Receiver Bitrate: 3.98 Mbps (4.97%) (too low! < 99%)
 Jitter          : 3.847 ms
-Packet Loss     : 0.038 % (too high! > 0%)
+Packet Loss     : 0.038% (too high! > 0%)

ci-scripts/tests/log/iperf_udp_msg_nok3.txt

@@ -1,4 +1,4 @@
-Sender Bitrate  : 1.03  Mbps
-Receiver Bitrate: 0.00  Mbps (too low! < 99%)
+Sender Bitrate  : 1.03 Mbps
+Receiver Bitrate: 0.00 bps (0.00%) (too low! < 99%)
 Jitter          : 0.000 ms
-Packet Loss     : 0 %
+Packet Loss     : 0%

ci-scripts/tests/log/iperf_udp_msg_ok.txt

@@ -1,4 +1,4 @@
-Sender Bitrate  : 1.00  Mbps
-Receiver Bitrate: 1.00  Mbps (99.60 %)
+Sender Bitrate  : 996.00 Kbps
+Receiver Bitrate: 996.00 Kbps (99.60%)
 Jitter          : 0.029 ms
-Packet Loss     : 0 %
+Packet Loss     : 0%

ci-scripts/tests/log/iperf_udp_msg_ok2.txt

@@ -1,4 +1,4 @@
-Sender Bitrate  : 4.67  Mbps
-Receiver Bitrate: 4.67  Mbps (100.00 %)
+Sender Bitrate  : 4.67 Mbps
+Receiver Bitrate: 4.67 Mbps (100.00%)
 Jitter          : 3.413 ms
-Packet Loss     : 0 %
+Packet Loss     : 0%