[FLINK-15332][jepsen] Copy flink-s3-fs-hadoop* into /plugins director…

…y instead of lib

We can no longer copy the flink-s3-fs-hadoop* jars into lib as they contain un-relocated
Hadoop 3.1.0 dependencies.

This closes apache#10634.

flink-jepsen/src/jepsen/flink/db.clj

@@ -89,7 +89,7 @@
  (info "Installing Flink from" url)
  (cu/install-archive! url install-dir)
  (info "Enable S3 FS")
- (c/exec (c/lit (str "ls " install-dir "/opt/flink-s3-fs-hadoop* | xargs -I {} mv {} " install-dir "/lib")))
+ (c/exec (c/lit (str "mkdir " install-dir "/plugins/s3-fs-hadoop && ls " install-dir "/opt/flink-s3-fs-hadoop* | xargs -I {} mv {} " install-dir "/plugins/s3-fs-hadoop")))
  (upload-job-jars! (->> test :test-spec :jobs (map :job-jar)))
  (write-configuration! test node)))