Remove challenged test for kbd name computation

[cookiecrook]

@ aleventhal wrote:

I think there's an error in the comp_tooltip.html test:

<kbd title="Control + Option" data-expectedlabel="Control + Option" data-testname="kbd with tooltip label" class="ex">CTRL + OPT</kbd>

According to the kbd table in HTML, many platforms do not have an accessible object for the kbd element. See https://w3c.github.io/html-aam/#el-kbd

If there's no accessible object, how can there be a name from the title attribute?

Originally posted by @aleventhal in #78 (comment)

[cookiecrook]

Can either move test to a respective .tentative file or comment el-kbd -> link with a link to this issue.

[aleventhal]

See also w3c/html-aam#552, where it's discussed whether moving the title to the description automatically for name-prohibited roles makes sense.