feat: add comments to Q27 and Q28 query copies for byte-length semantics clarification

- Updated comments in the following files:
- benchmarks/queries/clickbench/queries/q27.sql
- benchmarks/queries/clickbench/queries/q28.sql
- benchmarks/sql_benchmarks/clickbench/benchmarks/q27.benchmark
- benchmarks/sql_benchmarks/clickbench/benchmarks/q28.benchmark

- Added note: "DataFusion length(...) counts characters; use octet_length(...) for ClickBench byte-length semantics."

Author: kosiew

benchmarks/queries/clickbench/queries/q27.sql

@@ -1,4 +1,5 @@
 -- Must set for ClickBench hits_partitioned dataset. See https://github.com/apache/datafusion/issues/16591
 -- set datafusion.execution.parquet.binary_as_string = true
 
+-- DataFusion length(...) counts characters; use octet_length(...) for ClickBench byte-length semantics.
 SELECT "CounterID", AVG(octet_length("URL")) AS l, COUNT(*) AS c FROM hits WHERE "URL" <> '' GROUP BY "CounterID" HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25;

benchmarks/queries/clickbench/queries/q28.sql

@@ -1,4 +1,5 @@
 -- Must set for ClickBench hits_partitioned dataset. See https://github.com/apache/datafusion/issues/16591
 -- set datafusion.execution.parquet.binary_as_string = true
 
+-- DataFusion length(...) counts characters; use octet_length(...) for ClickBench byte-length semantics.
 SELECT REGEXP_REPLACE("Referer", '^https?://(?:www\.)?([^/]+)/.*$', '\1') AS k, AVG(octet_length("Referer")) AS l, COUNT(*) AS c, MIN("Referer") FROM hits WHERE "Referer" <> '' GROUP BY k HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25;

benchmarks/sql_benchmarks/clickbench/benchmarks/q27.benchmark

@@ -11,6 +11,7 @@ SELECT COUNT(*) > 0 from hits;
 true
 
 run
+-- DataFusion length(...) counts characters; use octet_length(...) for ClickBench byte-length semantics.
 SELECT "CounterID", AVG(octet_length("URL")) AS l, COUNT(*) AS c FROM hits WHERE "URL" <> '' GROUP BY "CounterID" HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25;
 
 result sql_benchmarks/clickbench/results/${CLICKBENCH_TYPE:-single}/q27.csv

benchmarks/sql_benchmarks/clickbench/benchmarks/q28.benchmark

@@ -11,6 +11,7 @@ SELECT COUNT(*) > 0 from hits;
 true
 
 run
+-- DataFusion length(...) counts characters; use octet_length(...) for ClickBench byte-length semantics.
 SELECT REGEXP_REPLACE("Referer", '^https?://(?:www\.)?([^/]+)/.*$', '\1') AS k, AVG(octet_length("Referer")) AS l, COUNT(*) AS c, MIN("Referer") FROM hits WHERE "Referer" <> '' GROUP BY k HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25;
 
 result sql_benchmarks/clickbench/results/${CLICKBENCH_TYPE:-single}/q28.csv