ci: use wait-for-it instead of just waiting for 10s

Signed-off-by: Vincent Fu <vincent.fu@samsung.com>

.github/actions/start-vm/action.yml

@@ -25,6 +25,9 @@ inputs:
 runs:
   using: "composite"
   steps:
+    - name: install wait-for-it
+      run: sudo apt install -y wait-for-it
+      shell: bash
     - name: Start VM in background
       run: |
         ${{ inputs.qemu }} \
@@ -43,7 +46,7 @@ runs:
       env:
         SSHCMD: ssh root@localhost -p ${{ inputs.ssh_fwd_port }}
     - name: Wait for VM to boot
-      run: sleep 10
+      run: wait-for-it localhost:${{ inputs.ssh_fwd_port }} -t 15
       shell: bash
     - name: Add guest host key to known_hosts
       run: |