Upgrade to Java 25 (#3000)

Error-prone introduced many more checks in Java 25. We fixed a few
and suppressed most. A follow-up bug is opened to clean this up.
An ai agent should be able to clean up most of it.

This PR is created with gemini-cli. Summary of experience:

* The good: AI caught most compatibility issues, and with permission,
  suppressed them through compiler flags and errorprone options.
  It also caught many versio references in scripts.

* Where it didn't shine:
  - It did not find and update the target version spec in the custome
    VKey annotation processor source file.
  - It did not flag eclipse-temurin:21 docker image for upgrade.
  - When running into failure, its first instinct is to disable checks
    e.g., -Werror instead of fixing them.

release/builder/build.sh

@@ -42,7 +42,7 @@ apt-get install gnupg2 -y
 apt-get install graphviz -y
 
 # Install Java
-apt-get install openjdk-21-jdk-headless -y
+apt-get install openjdk-25-jdk-headless -y
 
 # Install Python
 apt-get install python3 -y