btrfs-progs: ci: schedule expensive workflows to run weekly

Don't run the sanitizer workflow on each devel push as this takes about
45 minutes and consumes the free minutes. The coverage takes about 25
minutes but it's run on demand.

Allow the workflows run weekly on Tuesday noon so any eventual problems
are at least noticed.

[ci skip]

Signed-off-by: David Sterba <dsterba@suse.com>

Author: kdave

.github/workflows/coverage.yml

@@ -7,6 +7,9 @@ on:
     branches:
       - coverage-test
       - master
+  schedule:
+    - cron: '12 0 * * 1'
+
 jobs:
   build:
     runs-on: ubuntu-24.04

.github/workflows/sanitize.yml

@@ -8,9 +8,11 @@ run-name: Sanitizer checks
 on:
   push:
     branches:
-      - devel
       - sanitize-test
       - master
+  schedule:
+    - cron: '12 0 * * 1'
+
 jobs:
   build-ubsan:
     runs-on: ubuntu-24.04