Speedup ByteArray.indexOf (#83454)

We can do a faster indexOf on a bytes array by implementing a tight
array loop. Noticed while looking at bulk indexing profiling.

Author: original-brownbear

server/src/main/java/org/elasticsearch/common/bytes/BytesArray.java

@@ -55,6 +55,16 @@ public byte get(int index) {
         return bytes[offset + index];
     }
 
+    @Override
+    public int indexOf(byte marker, int from) {
+        for (int i = offset + from; i < offset + length; i++) {
+            if (bytes[i] == marker) {
+                return i - offset;
+            }
+        }
+        return -1;
+    }
+
     @Override
     public int length() {
         return length;