Fix pulsar website build ci (apache#8515)

### Motivation

Currently, pulsar-website-build ci will fail to build due to insufficient space. The error is as follows:

```
System.IO.IOException: No space left on device
   at System.IO.FileStream.WriteNative(ReadOnlySpan`1 source)
   at System.IO.FileStream.FlushWriteBuffer()
   at System.IO.FileStream.Flush(Boolean flushToDisk)
   at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
   at System.Diagnostics.TextWriterTraceListener.Flush()
   at GitHub.Runner.Common.HostTraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id)
   at GitHub.Runner.Common.HostTraceListener.TraceEvent(TraceEventCache eventCache, String source, TraceEventType eventType, Int32 id, String message)
   at System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String message)
   at GitHub.Runner.Common.Tracing.Info(String message)
   at GitHub.Runner.Worker.Worker.RunAsync(String pipeIn, String pipeOut)
   at GitHub.Runner.Worker.Program.MainAsync(IHostContext context, String[] args)
System.IO.IOException: No space left on device
   at System.IO.FileStream.WriteNative(ReadOnlySpan`1 source)
   at System.IO.FileStream.FlushWriteBuffer()
   at System.IO.FileStream.Flush(Boolean flushToDisk)
   at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
   at System.Diagnostics.TextWriterTraceListener.Flush()
```

So, we try to add a clean disk operation to see if we can fix this problem.

### Modifications

- Add `clean disk` steps for ci workflow
- Adjust the scheduled time

.github/workflows/ci-pulsar-website-build.yaml

@@ -42,6 +42,14 @@ jobs:
       - name: build
         run: mvn clean package -DskipTests -Pswagger
 
+      - name: clean disk
+        run: |
+          sudo swapoff -a
+          sudo rm -rf /swapfile /usr/share/dotnet /usr/local/lib/android /opt/ghc
+          sudo apt clean
+          docker rmi $(docker images -q) -f
+          df -h
+
       - name: publish
         env:
           GH_TOKEN: ${{ secrets.PULSARBOT_TOKEN }}