test: handle empty prefix in WebDAV href pattern matching

Fix regex pattern construction in assertXpathValueMatchesPattern when
prefixRemotePhp is empty. Previously, empty prefix resulted in double
slash patterns (//dav/...) that failed to match actual single slash
href values (/dav/...).

Resolves "Unknown modifier 'd'" regex error in WebDAV property tests.

Author: LukasHirt

tests/acceptance/bootstrap/WebDavPropertiesContext.php

@@ -1002,7 +1002,12 @@ public function assertXpathValueMatchesPattern(
 			$pattern = \preg_replace("/^\^/", "", $pattern);
 			$pattern = \ltrim($pattern, "\/");
 			$prefixRemotePhp = \rtrim(WebdavHelper::prefixRemotePhp(""), "/");
-			$pattern = "/^\/{$prefixRemotePhp}\/{$pattern}";
+
+      if ($prefixRemotePhp === '') {
+        $pattern = "/^\/{$pattern}";
+      } else {
+        $pattern = "/^\/{$prefixRemotePhp}\/{$pattern}";
+      }
 		}
 		$pattern = $this->featureContext->substituteInLineCodes(
 			$pattern,

tests/acceptance/features/coreApiWebdavOperations/propfind.feature

@@ -48,7 +48,7 @@ Feature: PROPFIND
       | password        | %public% |
     When the public sends "PROPFIND" request to the last public link share using the public WebDAV API with password "%public%"
     Then the HTTP status code should be "207"
-    And the value of the item "//d:href" in the response should match "/\*/dav\/public-files\/%public_token%\/$/"
+    And the value of the item "//d:href" in the response should match "/\/dav\/public-files\/%public_token%\/$/"
     And the value of the item "//oc:public-link-share-owner" in the response should be "Alice"
 
   @skipOnReva @issue-10071 @issue-10331