test-ob-sqlite.el: Don't load ob-sqlite

* testing/lisp/test-ob-sqlite.el (ob-sqlite): Don't explicitly load
ob-sqlite.

ob-LANG tests check whether the corresponding ob- feature is
available, signaling missing-test-dependency if it's not.  Which ob-
libraries are loaded/tested can then controlled by the Makefile
variable BTEST_OB_LANGUAGES.

test-ob-sqlite.el, however, requires ob-sqlite before its featurep
call, unconditionally loading ob-sqlite and breaking the above setup.

testing/lisp/test-ob-sqlite.el

@@ -20,7 +20,6 @@
 
 ;;; Code:
 (org-test-for-executable "sqlite3")
-(require 'ob-sqlite)
 (unless (featurep 'ob-sqlite)
   (signal 'missing-test-dependency "Support for sqlite code blocks"))