fix: address lint, compiler, and Error Prone warnings (#1692)

- Add missing `@Override` annotations to `RenderTask#run` and KML/GeoJSON Layer methods.
- Resolve `LockNotBeforeTry` warnings in clustering renderers by moving lock acquisition outside of `try` blocks and ensuring release inside `finally` blocks.
- Specify `Locale.ROOT` for filename casing comparisons in `KmlLayer` to satisfy `StringCaseLocaleUsage`.
- Refactor KML ground overlay mapping to collect updates before applying, preventing ConcurrentModificationExceptions during iteration.
- Sort imports in `KmlLayer` alphabetically to satisfy strict Checkstyle `ImportOrder` checks.
- Address generic rawtype compiler warnings by cleaning up `KmlContainerParser` generics and using safe suppression in `GeoJsonLayer`.