Remove previous preloads even on non-preload test

Because it is set by the installer and may also be set by the user, it
is important to not let the tests be affected by the global preload.
Setting the global preload again will not preload, as qubesd is not
running.

For: QubesOS/qubes-issues#1512

Author: ben-grande

tests/dispvm_perf.py

@@ -543,17 +543,16 @@ def run_test(self, test: TestConfig):
                 f"{gui_prefix} {target} allow\n"
                 f"{nogui_prefix} {target} allow\n"
             )
-        if test.preload_max:
-            orig_preload_threshold = self.dom0.features.get(
-                "preload-dispvm-threshold"
-            )
-            orig_preload_max = self.dom0.features.get("preload-dispvm-max")
-            if orig_preload_threshold is not None:
-                logger.info("Deleting threshold feature")
-                del self.dom0.features["preload-dispvm-threshold"]
-            if orig_preload_max is not None:
-                logger.info("Deleting global max feature")
-                del self.dom0.features["preload-dispvm-max"]
+        orig_preload_threshold = self.dom0.features.get(
+            "preload-dispvm-threshold"
+        )
+        orig_preload_max = self.dom0.features.get("preload-dispvm-max")
+        if orig_preload_threshold is not None:
+            logger.info("Deleting threshold feature")
+            del self.dom0.features["preload-dispvm-threshold"]
+        if orig_preload_max is not None:
+            logger.info("Deleting global max feature")
+            del self.dom0.features["preload-dispvm-max"]
         try:
             if test.preload_max:
                 preload_max = test.preload_max
@@ -581,21 +580,19 @@ def run_test(self, test: TestConfig):
                 logger.info("Deleting local max feature")
                 del self.dvm.features["preload-dispvm-max"]
                 self.wait_for_dispvm_destroy(old_preload)
-                if orig_preload_threshold is not None:
-                    logger.info(
-                        "Setting the original threshold feature: '%s'",
-                        orig_preload_threshold,
-                    )
-                    self.dom0.features["preload-dispvm-threshold"] = (
-                        orig_preload_threshold
-                    )
-                if orig_preload_max is not None:
-                    logger.info(
-                        "Setting the global max feature: '%s'", orig_preload_max
-                    )
-                    self.dom0.features["preload-dispvm-max"] = orig_preload_max
-                    if orig_preload_max != 0:
-                        asyncio.run(self.wait_preload(orig_preload_max))
+            if orig_preload_threshold is not None:
+                logger.info(
+                    "Setting the original threshold feature: '%s'",
+                    orig_preload_threshold,
+                )
+                self.dom0.features["preload-dispvm-threshold"] = (
+                    orig_preload_threshold
+                )
+            if orig_preload_max is not None:
+                logger.info(
+                    "Setting the global max feature: '%s'", orig_preload_max
+                )
+                self.dom0.features["preload-dispvm-max"] = orig_preload_max
             os.unlink(POLICY_FILE)
             if not os.getenv("QUBES_TEST_SKIP_TEARDOWN_SLEEP"):
                 logger.info("Load before sleep: '%s'", get_load())