reusable_build: provide info about disk usage before and after build

Currently we've CI workflows failing due to:

 cp: error writing '/__w/openwrt/openwrt/openwrt/build_dir/target-aarch64-openwrt-linux-musl_musl/linux-mediatek_filogic/linux-6.6.60.141efc9e/net/netfilter/ipvs/ip_vs_wrr.ko': No space left on device
 cp: error writing '/__w/openwrt/openwrt/openwrt/build_dir/target-aarch64-openwrt-linux-musl_musl/linux-mediatek_filogic/linux-6.6.60.41081c68/tools/perf/pmu-events/arch/s390/cf_z196/crypto.json': No space left on device
 cp: error writing '/__w/openwrt/openwrt/openwrt/build_dir/target-aarch64-openwrt-linux-musl_musl/linux-mediatek_filogic/linux-6.6.60.141efc9e/net/netfilter/ipvs/.ip_vs.ko.cmd': No space left on device
 cp: error writing '/__w/openwrt/openwrt/openwrt/build_dir/target-aarch64-openwrt-linux-musl_musl/linux-mediatek_filogic/linux-6.6.60.141efc9e/net/netfilter/ipvs/.ip_vs_lc.ko.

So in such cases, lets make the post mortem debugging a bit easier and
provide information about runner disk space before and after the build.

Signed-off-by: Petr Štetiar <ynezz@true.cz>

Author: ynezz

.github/workflows/reusable_build.yml

@@ -285,6 +285,11 @@ jobs:
         with:
           path: openwrt
 
+      - name: Provide information about disk usage before the build
+        shell: su buildbot -c "sh -e {0}"
+        working-directory: openwrt
+        run: df -h . ; du -sh .
+
       - name: Checkout packages feed
         if: inputs.include_feeds == true
         uses: actions/checkout@v4
@@ -684,6 +689,11 @@ jobs:
           name: ${{ inputs.target }}-${{ inputs.subtarget }}${{ inputs.testing == true && '-testing' || '' }}-logs
           path: "openwrt/logs"
 
+      - name: Provide information about disk usage after the build
+        shell: su buildbot -c "sh -e {0}"
+        working-directory: openwrt
+        run: df -h . ; du -sh .
+
       - name: Cleanup dl/build_dir/staging_dir to make some space
         working-directory: openwrt
         if: github.event_name == 'push'