docs: Update integration testing guide to include a hint to do a clean build when experiencing issues (#1584)

Author: QuChen88

docs/development-guide/IntegrationTests.md

@@ -69,3 +69,15 @@ cmd /c ./gradlew --no-parallel --no-daemon test-all-environments
 ```
 
 Test results can be found at `wrapper/build/report/index.html`.
+
+If you encounter unexplained build issues/errors, or after major project structure changes, try running the following to perform a clean build:
+
+macOS:
+```bash
+./gradlew clean
+```
+
+Windows:
+```bash
+cmd /c ./gradlew clean
+```