migrating to rbe_preconfig and remove bazel_toolchains (#1524)

diff --git a/examples/WORKSPACE.bazel b/examples/WORKSPACE.bazel
index a9ca080..afa56db 100644
--- a/examples/WORKSPACE.bazel
+++ b/examples/WORKSPACE.bazel
@@ -136,18 +136,18 @@
 ###############################################################################
 
 http_archive(
-    name = "bazel_toolchains",
-    sha256 = "179ec02f809e86abf56356d8898c8bd74069f1bd7c56044050c2cd3d79d0e024",
-    strip_prefix = "bazel-toolchains-4.1.0",
-    urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/releases/download/4.1.0/bazel-toolchains-4.1.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-toolchains/releases/download/4.1.0/bazel-toolchains-4.1.0.tar.gz",
-    ],
+    name = "bazelci_rules",
+    sha256 = "eca21884e6f66a88c358e580fd67a6b148d30ab57b1680f62a96c00f9bc6a07e",
+    strip_prefix = "bazelci_rules-1.0.0",
+    url = "https://github.com/bazelbuild/continuous-integration/releases/download/rules-1.0.0/bazelci_rules-1.0.0.tar.gz",
 )
 
-load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")
+load("@bazelci_rules//:rbe_repo.bzl", "rbe_preconfig")
 
 # Creates a default toolchain config for RBE.
 # Use this as is if you are using the rbe_ubuntu16_04 container,
 # otherwise refer to RBE docs.
-rbe_autoconfig(name = "buildkite_config")
+rbe_preconfig(
+    name = "buildkite_config",
+    toolchain = "ubuntu1804-bazel-java11",
+)
diff --git a/examples/crate_universe/WORKSPACE.bazel b/examples/crate_universe/WORKSPACE.bazel
index c0c6371..c743345 100644
--- a/examples/crate_universe/WORKSPACE.bazel
+++ b/examples/crate_universe/WORKSPACE.bazel
@@ -321,18 +321,18 @@
 
 # Used for Bazel CI
 http_archive(
-    name = "bazel_toolchains",
-    sha256 = "179ec02f809e86abf56356d8898c8bd74069f1bd7c56044050c2cd3d79d0e024",
-    strip_prefix = "bazel-toolchains-4.1.0",
-    urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/releases/download/4.1.0/bazel-toolchains-4.1.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-toolchains/releases/download/4.1.0/bazel-toolchains-4.1.0.tar.gz",
-    ],
+    name = "bazelci_rules",
+    sha256 = "eca21884e6f66a88c358e580fd67a6b148d30ab57b1680f62a96c00f9bc6a07e",
+    strip_prefix = "bazelci_rules-1.0.0",
+    url = "https://github.com/bazelbuild/continuous-integration/releases/download/rules-1.0.0/bazelci_rules-1.0.0.tar.gz",
 )
 
-load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")
+load("@bazelci_rules//:rbe_repo.bzl", "rbe_preconfig")
 
 # Creates a default toolchain config for RBE.
 # Use this as is if you are using the rbe_ubuntu16_04 container,
 # otherwise refer to RBE docs.
-rbe_autoconfig(name = "buildkite_config")
+rbe_preconfig(
+    name = "buildkite_config",
+    toolchain = "ubuntu1804-bazel-java11",
+)