Update default Java language version

Use `--java_language_version=''` to mean the toolchain-defined default version,
instead of hard-coding a default value of the flag.

PiperOrigin-RevId: 495444503
Change-Id: Ie6554d85a8c64d2ecd78ff9a977f48d23edbc52b
diff --git a/scripts/bootstrap/bootstrap.sh b/scripts/bootstrap/bootstrap.sh
index a2c7b0a..7a0040e 100755
--- a/scripts/bootstrap/bootstrap.sh
+++ b/scripts/bootstrap/bootstrap.sh
@@ -36,7 +36,7 @@
       --strategy=Javac=worker --worker_quit_after_build --ignore_unsupported_sandboxing \
       --compilation_mode=opt \
       --distdir=derived/distdir \
-      --extra_toolchains=//scripts/bootstrap:bootstrap_toolchain_definition \
+      --extra_toolchains=//scripts/bootstrap:all \
       ${DIST_BOOTSTRAP_ARGS:-} \
       ${EXTRA_BAZEL_ARGS:-}"