PYTHON-4033 Address perf test UserWarning (#1422)

Author: blink1073

.evergreen/perf.yml

@@ -26,7 +26,7 @@ timeout:
 
 functions:
   "fetch source":
-    # Executes git clone and applies the submitted patch, if any
+    # Executes clone and applies the submitted patch, if any
     - command: git.get_project
       params:
         directory: "src"
@@ -67,7 +67,6 @@ functions:
            PROJECT_DIRECTORY: "$PROJECT_DIRECTORY"
            PREPARE_SHELL: |
               set -o errexit
-              set -o xtrace
               export DRIVERS_TOOLS="$DRIVERS_TOOLS"
               export MONGO_ORCHESTRATION_HOME="$MONGO_ORCHESTRATION_HOME"
               export MONGODB_BINARIES="$MONGODB_BINARIES"

test/performance/perf_test.py

@@ -122,7 +122,9 @@ def runTest(self):
         self.max_iterations = NUM_ITERATIONS
         for i in range(NUM_ITERATIONS):
             if time.monotonic() - start > MAX_ITERATION_TIME:
-                warnings.warn("Test timed out, completed %s iterations." % i)
+                with warnings.catch_warnings():
+                    warnings.simplefilter("default")
+                    warnings.warn("Test timed out, completed %s iterations." % i)
                 break
             self.before()
             with Timer() as timer: