tests: fix new pylint issues

New version of Pylint complains about a few
`possibly-used-before-assignment`.

Signed-off-by: Pablo Barbáchano <[email protected]>

Author: pb8o

tests/integration_tests/functional/test_cpu_features.py

@@ -686,6 +686,7 @@ def test_cpu_template(uvm_plain_any, cpu_template, microvm_factory):
 def check_masked_features(test_microvm, cpu_template):
     """Verify the masked features of the given template."""
     # fmt: off
+    must_be_unset = []
     if cpu_template == "C3":
         must_be_unset = [
             (0x1, 0x0, "ecx",

tests/integration_tests/functional/test_topology.py

@@ -43,6 +43,7 @@ def _check_cache_topology_x86(
     )
 
     cpu_vendor = utils.get_cpu_vendor()
+    expected_level_1_topology = expected_level_3_topology = None
     if cpu_vendor == utils.CpuVendor.AMD:
         key_share = "extra cores sharing this cache"
         expected_level_1_topology = {

tests/integration_tests/performance/test_rate_limiter.py

@@ -440,6 +440,7 @@ def _process_iperf_line(line):
 def _process_iperf_output(iperf_out):
     """Parse iperf3 output and return average test time and bandwidth."""
     iperf_out_lines = iperf_out.splitlines()
+    send_time = send_bw = rcv_time = rcv_bw = None
     for line in iperf_out_lines:
         if line.find("sender") != -1:
             send_time, send_bw = _process_iperf_line(line)