Fix test failures of JavaHL with Java 25 on Windows due to that deleting a
file with readonly flag on Windows fails since Java 25.

https://bugs.openjdk.org/browse/JDK-8355954

* subversion/bindings/javahl/tests/org/apache/subversion/javahl/SVNTests.java
  (createDirectories):
    Add `throws IOException`.
  (removeDirOrFile):
    Unset readonly flag of the file before deleting the file and add
    `throws IOException`.

* subversion/bindings/javahl/tests/org/tigris/subversion/javahl/SVNTests.java
  (createDirectories, removeDirOrFile): Ditto.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1930973 13f79535-47bb-0310-9956-ffa450edef68