Clear externalDependency and testDependency cached files periodically

The directories `/home/jenkins/externalDependency/` and `/home/jenkins/testDependency` are cached dependency files used in perf or system tests. If these directories do not have the latest files, the tests will fail. Two solutions to this are
- Periodically delete these directories, or whenever a change to the files is detected upstream, delete the cache
- A solution on the test side is to check to see if the cached files are up to date before running the test

Start by locating the perf or system tests that use /home/jenkins/externalDependency/ and /home/jenkins/testDependency, then inspect how those cached files are populated and consumed. Compare the proposed cleanup and freshness-check approaches, and define done as ensuring tests do not run with outdated dependency files.

Written by the indexing model from the issue text.