Fix regression with opaque URI determination

Before RfcUriParser we expected opaque URI's to not have ":/"
after the scheme while the new parser expect opaque URI's to
not have a slash anywhere after the scheme. This commit
restores the previous behavior.

Closes gh-34588

spring-web/src/main/java/org/springframework/web/util/RfcUriParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -503,8 +503,7 @@ abstract class RfcUriParser {
 		// Component capture
 
 		public InternalParser resolveIfOpaque() {
-			boolean hasSlash = (this.uri.indexOf('/', this.index + 1) == -1);
-			this.isOpaque = (hasSlash && !hierarchicalSchemes.contains(this.scheme));
+			this.isOpaque = (this.uri.charAt(this.index) != '/' && !hierarchicalSchemes.contains(this.scheme));
 			return this;
 		}