CI: Remove obsolete steps from musl.yml

These have become obsolete with the use of `./.github/actions/setup-vtest` in
6e67b59aca11e8262c424fce062a09784d3da2ba.

.github/workflows/musl.yml

@@ -18,7 +18,6 @@ jobs:
       steps:
       - name: Setup coredumps
         run: |
-          ulimit -c unlimited
           echo '/tmp/core/core.%h.%e.%t' > /proc/sys/kernel/core_pattern
       - uses: actions/checkout@v6
       - name: Install dependencies
@@ -30,9 +29,6 @@ jobs:
         run: ./haproxy -vv
       - name: Show linked libraries
         run: ldd haproxy
-      - name: Install problem matcher for VTest
-        # This allows one to more easily see which tests fail.
-        run: echo "::add-matcher::.github/vtest.json"
       - name: Run VTest
         id: vtest
         run: make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel