Added tests for recent block combos

Signed-off-by: Nana Essilfie-Conduah <nana@swirldslabs.com>

Author: Nana-EC

block-node/backfill/src/main/java/org/hiero/block/node/backfill/BackfillPlugin.java

@@ -288,7 +288,7 @@ private void detectGaps() {
                 detectedGaps = new ArrayList<>();
                 detectedGaps.add(detectedRecentGapRange);
 
-                // backfile recent gaps first to prioritize staying close to the network
+                // backfill recent gaps first to prioritize staying close to the network
                 LOGGER.log(
                         TRACE,
                         "Detected recent gaps, numGaps={0} totalMissingBlocks={1}",