Problem:    Tests fail when the float feature is disabled.
Solution:   Skip tests that don't work without float support.

https://github.com/vim/vim/commit/5feabe00c47fa66d5f4c95213f150488433f78e3

Cherry-pick Test_ruby_Vim_blob() from patch 8.1.0977 and skip it.

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    Temp files remain after running tests.
Solution:   Delete the right files. (Dominique Pellé, closes vim/vim#8509)

https://github.com/vim/vim/commit/6c72fd51a899e6f0c272b08b9784d3c7a3cede20

Co-authored-by: Dominique Pelle <dominique.pelle@gmail.com>

The new oldtest directory is in test/old/testdir. The reason for this is
that many tests have hardcoded the parent directory name to be
'testdir'.