## What changes were proposed in this pull request?

Move all existing tests to non-installed directory so that it will never run by installing SparkR package

For a follow-up PR:
- remove all skip_on_cran() calls in tests
- clean up test timer
- improve or change basic tests that do run on CRAN (if anyone has suggestion)

It looks like `R CMD build pkg` will still put pkg\tests (ie. the full tests) into the source package but `R CMD INSTALL` on such source package does not install these tests (and so `R CMD check` does not run them)

## How was this patch tested?

- [x] unit tests, Jenkins
- [x] AppVeyor
- [x] make a source package, install it, `R CMD check` it - verify the full tests are not installed or run

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #18264 from felixcheung/rtestset.