Remove the on schedule event on scorecards. (#4749)

Scorecards is failing because it relies on an environment variable that
do not exist on cron jobs. Since we are running the workflow on every PR
we can safely delete the the scheduled one.
diff --git a/.github/workflows/scorecards-analysis.yml b/.github/workflows/scorecards-analysis.yml
index 1256ec9..5148f2e 100644
--- a/.github/workflows/scorecards-analysis.yml
+++ b/.github/workflows/scorecards-analysis.yml
@@ -2,8 +2,6 @@
 on:
   # Only the default branch is supported.
   branch_protection_rule:
-  schedule:
-    - cron: '15 19 * * 6'
   push:
     branches: [ main ]