tf-m-nightly-code-coverage: Temporarily switch to build every other day

Building weekly is too infrequently and may "mask" issues. Build more
frequently after the latest round of fixes, to make sure that the job
is actually stable now.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I4b1fd8c086e1c9620d6723ce64deb39069964d38
1 file changed