ORC-2132: Use Java 26 instead of 26-ea

### What changes were proposed in this pull request?

This PR replaces `26-ea` (early access) with the GA release `26` for the Java version used in the `build_and_test.yml` GitHub Actions workflow.

### Why are the changes needed?

Java 26 has been released as GA, so we should use the stable release instead of the early-access version.

### How was this patch tested?

Pass the GitHub Actions workflow with the updated Java version.

### Was this patch authored or co-authored using generative AI tooling?

Generated-by: Claude Code (claude-opus-4-6)

Closes #2581 from dongjoon-hyun/ORC-2132.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
(cherry picked from commit ebd9e98)
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

Author: dongjoon-hyun

.github/workflows/build_and_test.yml

@@ -88,7 +88,7 @@ jobs:
             java: 17
             cxx: clang++
           - os: ubuntu-latest
-            java: 26-ea
+            java: 26
             cxx: clang++
     env:
       MAVEN_OPTS: -Xmx2g