[GH Actions] Add "Disk Usage" step to Android workflows

Summary:
Just so we can see where we're at with disk usage + monitor things going forward.

Example output:
{F669336}

---

Depends on D8689

Test Plan: Will land and see what happens.

Reviewers: ashoat, ginsu, jon, tomek, marcin

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D8690

.github/workflows/android_ci.yml

@@ -47,3 +47,6 @@ jobs:
         env:
           ANDROID_SIGNING_PASSWORD: ${{secrets.ANDROID_SIGNING_PASSWORD}}
         run: ./gradlew bundleRelease
+
+      - name: Disk Usage
+        run: df -h

.github/workflows/android_release.yml

@@ -58,3 +58,6 @@ jobs:
       - name: Upload to Google Play
         working-directory: ./native/android
         run: node upload-aab.js
+
+      - name: Disk Usage
+        run: df -h