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
diff --git a/tf-m-nightly-code-coverage.yaml b/tf-m-nightly-code-coverage.yaml
index 48208a1..48f9396 100644
--- a/tf-m-nightly-code-coverage.yaml
+++ b/tf-m-nightly-code-coverage.yaml
@@ -17,7 +17,7 @@
           days-to-keep: 90
           num-to-keep: 45
     triggers:
-      - timed: 'H 21 * * 6'
+      - timed: 'H 21 */2 * *'
     parameters:
       - string:
           name: 'FILTER_GROUP'