ci: clear out space on centos job

Clear out space on the centos job be deleteing unnecessary files.

Raised by #33293 which pointed to a solution like https://github.com/google/oss-fuzz/commit/b7f04d782277638a67bc44865de445977eed4708

Only runs when cache provider (runner) is `gha`, and on the CentOS job.

.github/actions/clear-files/action.yml

@@ -0,0 +1,12 @@
+name: 'Clear unnecessary files'
+description: 'Clear out unnecessary files to make space on the VM'
+runs:
+  using: 'composite'
+  steps:
+    - name: Clear unnecessary files
+      shell: bash
+      env:
+        DEBIAN_FRONTEND: noninteractive
+      run: |
+        set +o errexit
+        sudo bash -c '(ionice -c 3 nice -n 19 rm -rf /usr/share/dotnet/ /usr/local/graalvm/ /usr/local/.ghcup/ /usr/local/share/powershell /usr/local/share/chromium /usr/local/lib/android /usr/local/lib/node_modules)&'