Use defvar-keymap in tests

Use defvar-keymap in tests

* test/lisp/button-tests.el (button-tests--map):
* test/lisp/emacs-lisp/edebug-tests.el (edebug-tests-keymap):
* test/lisp/help-tests.el (help-tests-remap-map)
(help-tests-major-mode-map, help-tests-minor-mode-map):
* test/lisp/kmacro-tests.el (kmacro-tests-keymap):
* test/lisp/repeat-tests.el (repeat-tests-map)
(repeat-tests-repeat-map):
* test/src/keymap-tests.el (keymap-tests-minor-mode-map)
(keymap-tests-major-mode-map): Use defvar-keymap.