free disk space on CI runners

This change adds a script to significantly free up space on CI runners.

Before:
```
=== df -h ===
Filesystem      Size  Used Avail Use% Mounted on
/dev/root        72G   66G  5.8G  93% /
tmpfs           7.9G   84K  7.9G   1% /dev/shm
tmpfs           3.2G  1.2M  3.2G   1% /run
tmpfs           5.0M     0  5.0M   0% /run/lock
/dev/sda16      881M   62M  758M   8% /boot
/dev/sda15      105M  6.2M   99M   6% /boot/efi
/dev/sdb1        74G  4.1G   66G   6% /mnt
tmpfs           1.6G   12K  1.6G   1% /run/user/1001
```
After:
```
``

Author: jayshrivastava

.github/actions/setup/action.yml

@@ -14,27 +14,7 @@ runs:
   steps:
     - name: Free up disk space
       shell: bash
-      run: |
-        # Source: https://github.com/apache/flink/blob/02d30ace69dc18555a5085eccf70ee884e73a16e/tools/azure-pipelines/free_disk_space.sh
-        echo "=============================================================================="
-        echo "Freeing up disk space on CI system"
-        echo "=============================================================================="
-        echo "Listing 100 largest packages"
-        dpkg-query -Wf '${Installed-Size}\t${Package}\n' | sort -n | tail -n 100
-        df -h
-        echo "Removing large packages"
-        sudo apt-get remove -y '^ghc-8.*'
-        sudo apt-get remove -y '^dotnet-.*'
-        sudo apt-get remove -y '^llvm-.*'
-        sudo apt-get remove -y 'php.*'
-        sudo apt-get remove -y azure-cli google-cloud-sdk hhvm google-chrome-stable firefox powershell mono-devel
-        sudo apt-get autoremove -y
-        sudo apt-get clean
-        df -h
-        echo "Removing large directories"
-        # deleting 15GB
-        rm -rf /usr/share/dotnet/
-        df -h
+      run: ${{ github.action_path }}/free_disk_space.sh
     - shell: bash
       run: |
         echo $HOME

.github/actions/setup/free_disk_space.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+# Script to free up disk space on CI systems
+# Source: https://github.com/apache/flink/blob/02d30ace69dc18555a5085eccf70ee884e73a16e/tools/azure-pipelines/free_disk_space.sh
+
+echo "Freeing up disk space on CI system"
+
+echo "Listing 100 largest packages"
+dpkg-query -Wf '${Installed-Size}\t${Package}\n' | sort -n | tail -n 100
+df -h
+
+echo "Removing large packages"
+sudo apt-get remove -y '^ghc-8.*'
+sudo apt-get remove -y '^dotnet-.*'
+sudo apt-get remove -y '^llvm-.*'
+sudo apt-get remove -y 'php.*'
+sudo apt-get remove -y azure-cli google-cloud-sdk hhvm google-chrome-stable firefox powershell mono-devel
+sudo apt-get autoremove -y
+sudo apt-get clean
+df -h
+
+echo "Removing large directories"
+rm -rf /usr/share/dotnet/
+df -h