fix: handle cached file delete where path does not exist

While testing flakiness of disk-based cache delete metrics, it was found that eviction may happen from different reasons and the path may already be deleted.
To avoid a runtime exception (that is anyway shallowed by listener execution), this PR introduces some validation before checking size.

core/src/main/java/io/aiven/kafka/tieredstorage/fetch/cache/DiskChunkCache.java

@@ -98,11 +98,16 @@ public RemovalListener<ChunkKey, Path> removalListener() {
         return (key, path, cause) -> {
             try {
                 if (path != null) {
-                    final long fileSize = Files.size(path);
-                    Files.delete(path);
-                    metrics.chunkDeleted(fileSize);
-                    log.trace("Deleted cached file for key {} with path {} from cache directory."
-                        + " The reason of the deletion is {}", key, path, cause);
+                    if (Files.exists(path)) {
+                        final long fileSize = Files.size(path);
+                        Files.delete(path);
+                        metrics.chunkDeleted(fileSize);
+                        log.trace("Deleted cached file for key {} with path {} from cache directory."
+                            + " The reason of the deletion is {}", key, path, cause);
+                    } else {
+                        log.debug("Deletion of cached file for key {} with "
+                            + "path {} is requested by file is not found", key, path);
+                    }
                 } else {
                     log.warn("Path not present when trying to delete cached file for key {} from cache directory."
                         + " The reason of the deletion is {}", key, cause);