fix: also set release notes from file when file exists (#1081)

<!-- markdownlint-disable MD041 -->
#### What this PR does / why we need it

If the release notes file exists the release notes aren't properly set
into the environment which causes the release notes not to be applied to
the release correctly

#### Which issue(s) this PR fixes
<!--
Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
-->

.github/workflows/release.yaml

@@ -142,13 +142,13 @@ jobs:
         if [ ! -f "$f" ]; then
           echo "# Release ${{ env.RELEASE_VERSION }}" > "$f"
           echo "$RELEASE_NOTES" | tail -n +2 >> "$f"
-          echo "RELEASE_NOTES_FILE=$f" >> $GITHUB_ENV
           git add "$f"
           git commit -m "ReleaseNotes for $RELEASE_VERSION"
           git push origin ${GITHUB_REF#refs/heads/}
         else
           echo "Using release notes file $f from code base"
         fi
+        echo "RELEASE_NOTES_FILE=$f" >> $GITHUB_ENV
 
     - name: Create and Push Release
       env: