Set java on remote JDKs

If the `java` attribute on `java_runtime` isn't set, Bazel guesses it
based on the host platform, which can be different from the execution
platform.

https://github.com/bazelbuild/bazel/blob/04a05677e4714434ec196c45a4ccbd8e0ef2f0ff/src/main/java/com/google/devtools/build/lib/rules/java/JavaRuntime.java#L46

Work towards bazelbuild/bazel#19587

toolchains/jdk_build_file.bzl

@@ -83,6 +83,9 @@ java_runtime(
         ":jdk-lib",
         ":jre",
     ],
+    # Provide the 'java` binary explicitly so that the correct path is used by
+    # Bazel even when the host platform differs from the execution platform.
+    java = glob(["bin/java.exe", "bin/java"])[0],
     version = {RUNTIME_VERSION},
 )
 """