Fix bug finding dependency-graph files with 'download-and-submit'

[bigdaz]

When 'download-and-submit' was used, the correct DEPENDENCY_GRAPH_REPORT_DIR was not set and the action was not able to locate the downloaded files.

[github-actions]

Job Summary for Gradle

Demo adding Build Scan® comment to PR :: successful-build-with-always-comment

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
kotlin-dsl	build	8.7	✅

[github-actions]

Job Summary for Gradle

Demo adding Build Scan® comment to PR :: failing-build-with-comment-on-failure

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
kotlin-dsl	no-a-real-task	8.7	❌