Plugins: Make file system path handling in tests OS agnostic (#79651)

* make path handling OS agnostic

* PR feedback

* fix input for test case

pkg/infra/httpclient/httpclientprovider/http_logger_middleware_test.go

@@ -47,6 +47,8 @@ func TestHTTPLoggerMiddleware(t *testing.T) {
 		f, err := os.CreateTemp("", "example_*.har")
 		require.NoError(t, err)
 		defer func() {
+			err = f.Close()
+			require.NoError(t, err)
 			err := os.Remove(f.Name())
 			require.NoError(t, err)
 		}()