Use a JDK version-specific toolchain in bazel_java_test.sh

e.g. for ` //src/test/shell/bazel:bazel_java_test_jdk16_toolchain_head`,
this test was previously using `@bazel_tools//tools/jdk:toolchain`, which
was leaking the toolchain from the enclosing version of Bazel. It worked
anyways because turbine was always producing JDK 8 class files, but as of
google/turbine@006a74b
turbine uses the class file version corresponding to the `-target` or
`--release` flag.

This fixes e.g.

```
java/com/google/sandwich/B.java:3: error: cannot access C
  C myObject;
  ^
  bad class file: bazel-out/k8-fastbuild/bin/java/com/google/sandwich/libbottom-hjar.jar(/com/google/sandwich/C.class)
    class file has wrong version 59.0, should be 55.0
    Please remove or make sure it appears in the correct subdirectory of the classpath.
```

from #14059

PiperOrigin-RevId: 399738050

src/test/shell/bazel/bazel_java_test.sh

@@ -97,6 +97,13 @@ if [[ $# -gt 0 ]]; then
   JAVA_RUNTIME_VERSION="$1"; shift
   add_to_bazelrc "build --java_runtime_version=${JAVA_RUNTIME_VERSION}"
   add_to_bazelrc "build --tool_java_runtime_version=${JAVA_RUNTIME_VERSION}"
+  if [[ "${JAVA_RUNTIME_VERSION}" == 8 ]]; then
+    JAVA_TOOLCHAIN="@bazel_tools//tools/jdk:toolchain_java8"
+  elif [[ "${JAVA_RUNTIME_VERSION}" == 11 ]]; then
+    JAVA_TOOLCHAIN="@bazel_tools//tools/jdk:toolchain_java11"
+  else
+    JAVA_TOOLCHAIN="@bazel_tools//tools/jdk:toolchain_jdk_${JAVA_RUNTIME_VERSION}"
+  fi
 fi
 
 export TESTENV_DONT_BAZEL_CLEAN=1