In the past you could tell the nodes in a test cluster to attach themselves to a waiting debugger on startup by passing the `--debug-server-jvm` option documented here:

https://github.com/elastic/elasticsearch/blob/c0228c73fea5caf279bf7141eabea50813c4528b/TESTING.asciidoc#L383-L390

I think this changed in #92379 and no longer seems to work. In fact I really wanted to attach a debugger to just one of the nodes in the cluster, and I believe #92379 might make this much easier to use (e.g. maybe via a method `LocalNodeSpecBuilder#debuggerPort(int)`). That'd be even better.
test/test-clusters/src/main/java/org/elasticsearch/test/cluster/local/LocalClusterFactory.java
Writer writer = Files.newBufferedWriter(destination, StandardOpenOption.APPEND);
                            Reader reader = new BufferedReader(new InputStreamReader(rolesFile.asStream()))
                        ) {
                            reader.transferTo(writer);
                        } catch (IOException e) {
                            throw new UncheckedIOException("Failed to append roles file " + rolesFile + " to " + destination, e);
                        }
                    });
                }
                LOGGER.info("Creating users for node '{}'", spec.getName());
                for (User user : spec.getUsers()) {
                    try {
                        ProcessUtils.exec(
                            workingDir,
                            distributionDir.resolve("bin").resolve("elasticsearch-users"),
                            getEnvironmentVariables(),
                            false,
                            "useradd",
                            user.getUsername(),
                            "-p",
                            user.getPassword(),
                            "-r",
                            user.getRole()
                        ).waitFor();
                    } catch (InterruptedException e) {
                        throw new RuntimeException(e);
                    }
                }
            }
        }