ci: use Ubuntu 22.04 (#3083)

Update the CI configuration and start testing on Ubuntu 22.04.

Fixes #3084

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index dddc510..5c21366 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -95,7 +95,7 @@
 # otherwise refer to RBE docs.
 rbe_preconfig(
     name = "buildkite_config",
-    toolchain = "ubuntu1804-bazel-java11",
+    toolchain = "ubuntu2204",
 )
 
 local_repository(