more automated testing simplifications

- remove old automated scripts tied to Jenkins plugins
- remove deprecated Theta regression test environment
- updated README

darshan-test/automated/README.md

@@ -0,0 +1,11 @@
+This build script can be used by automated systems (e.g., Github workflows,
+Jenkins, other CI systems) to build/test the Darshan runtime library and
+associated tools.
+
+The followng environment variables can be set to influence the behavior of
+the script:
+ - DARSHAN\_INSTALL\_PREFIX - path to install Darshan
+ - DARSHAN\_LOG\_PATH - formatted path to store Darshan logs
+ - DARSHAN\_RUNTIME\_CONFIG\_ARGS - darshan-runtime config args
+ - DARSHAN\_UTIL\_CONFIG\_ARGS - darshan-util config args
+ - DARSHAN\_RUNTIME\_SKIP - skip darshan-runtime build if set