Update CI to use JDK 26.0.0-ea.27.0.ea

[wmdietl]

No description provided.

[wmdietl]

b27 seems to be the newest available in CI.

[wmdietl]

typecheck-part2 fails with JDK 26 with:

> Task :dataflow:checkResourceLeak
/home/runner/work/checker-framework/checker-framework/dataflow/src/main/java/org/checkerframework/dataflow/cfg/visualize/CFGVisualizeLauncher.java:321: error: [resourceleak:required.method.not.called] @MustCall method close may not have been invoked on child or any of its aliases.
            Process child = Runtime.getRuntime().exec(new String[] {"/bin/sh", "-c", command});
                    ^
  The type of object is: java.lang.Process.
  Reason for going out of scope: possible exceptional exit due to child.waitFor() with exception type java.lang.InterruptedException
1 error

[wmdietl]

Try ea29 again

[wmdietl]

ea29 still not available. Need to look into whether there was a compiler change that could lead to this issue.