patch 9.1.1937: tests: Test_matchfuzzy_initialized() fails

patch 9.1.1937: tests: Test_matchfuzzy_initialized() fails

Problem:  tests: Test_matchfuzzy_initialized() fails
Solution: Send a dummy key (Corey Hickey)

Test_matchfuzzy_initialized seems to expect that the 'lvimgrep' will be
interrupted by sending a SIGINT. If the search finishes beforehand,
though, then the SIGINT triggers vim to tell the user how to quit.

Vim does not show this message immediately, though; instead, vim shows
the message next time it is active. When StopVimInTerminal() sends a key
sequence intended to cause vim to quit, this activates vim to show the
message instead of quitting.

I do not understand every detail of the problem fully--if I type the
characters from StopVimInTerminal() into a post-SIGTERM terminal
directly, that seems to work ok; there seems to be a timing issue due to
sending all the characters at once.

This fix does make the test work reliably for me, and the test still
works even if I limit my CPU frequency so that the search is interrupted
by the SIGINT.

fixes: #18821
related: #18822

Signed-off-by: Corey Hickey <bugfood-c@fatooh.org>
Signed-off-by: Christian Brabandt <cb@256bit.org>