FileUrlResource.isWritable() exclusively relies on getFile() implementation

Closes gh-25584 (cherry picked from commit c6cc670)

Author: jhoeller

spring-core/src/main/java/org/springframework/core/io/FileUrlResource.java

@@ -90,15 +90,8 @@ public File getFile() throws IOException {
 @Override
 public boolean isWritable() {
 try {
-URL url = getURL();
-if (ResourceUtils.isFileURL(url)) {
-// Proceed with file system resolution
-File file = getFile();
-return (file.canWrite() && !file.isDirectory());
-}
-else {
-return true;
-}
+File file = getFile();
+return (file.canWrite() && !file.isDirectory());
 }
 catch (IOException ex) {
 return false;