[coverity] Fix 1566354 Resource leak

In the `test-platform` conformance test suite, ensure that the
`ur_loader_config_handle_t` is always cleaned up even in the event of
assert failures in `SetUp()` by releasing it in `TearDown()`.

test/conformance/platform/fixtures.h

@@ -14,12 +14,10 @@ struct urTest : ::testing::Test {
 
     void SetUp() override {
         ur_device_init_flags_t device_flags = 0;
-        ur_loader_config_handle_t config;
-        ASSERT_SUCCESS(urLoaderConfigCreate(&config));
-        ASSERT_SUCCESS(
-            urLoaderConfigEnableLayer(config, "UR_LAYER_FULL_VALIDATION"));
-        ASSERT_SUCCESS(urInit(device_flags, config));
-        ASSERT_SUCCESS(urLoaderConfigRelease(config));
+        ASSERT_SUCCESS(urLoaderConfigCreate(&loader_config));
+        ASSERT_SUCCESS(urLoaderConfigEnableLayer(loader_config,
+                                                 "UR_LAYER_FULL_VALIDATION"));
+        ASSERT_SUCCESS(urInit(device_flags, loader_config));
 
         uint32_t adapter_count;
         ASSERT_SUCCESS(urAdapterGet(0, nullptr, &adapter_count));
@@ -31,10 +29,14 @@ struct urTest : ::testing::Test {
         for (auto adapter : adapters) {
             ASSERT_SUCCESS(urAdapterRelease(adapter));
         }
+        if (loader_config) {
+            ASSERT_SUCCESS(urLoaderConfigRelease(loader_config));
+        }
         ur_tear_down_params_t tear_down_params{};
         ASSERT_SUCCESS(urTearDown(&tear_down_params));
     }
 
+    ur_loader_config_handle_t loader_config = nullptr;
     std::vector<ur_adapter_handle_t> adapters;
 };