test: exclude the two high-delay debounce tests from the valgrind CI run
As suspected when these tests were added in !630 (merged), they are among the leading causes for CI failures. This is not really the fault of the tests or of the code being tested; it's just a combination of the tests' tight timing requirements with valgrind moving at a snail's pace.
Let's leave them out of the valgrind run then, like the gestures_swipe_3fg_unaccel
test has done for a while. They still get run without valgrind, and they are less fickle in that environment.