[SPARK-48627][SQL] Perf improvement for binary to to HEX_DISCRETE string

[yaooqinn]

What changes were proposed in this pull request?

By replacing String.format, we can achieve nearly 200x performance improvement.

The SparkStringUtils.getHexString is widely used by

• the Spark Thrift Server to convert binary to string when sending results to clients
• the Spark SQL shell for display
• the Spark Shell when calling show
• the Spark Connect scala client when stringifying binaries in arrow vectors

+OpenJDK 64-Bit Server VM 17.0.10+0 on Mac OS X 14.5
+Apple M2 Max
+Cardinality 100000:                       Best Time(ms)   Avg Time(ms)   Stdev(ms)    Rate(M/s)   Per Row(ns)   Relative
+------------------------------------------------------------------------------------------------------------------------
+Spark                                             42210          43595        1207          0.0      422102.9       1.0X
+Java                                                238            243           2          0.4        2381.9     177.2X 

Why are the changes needed?

perf improvement

Does this PR introduce any user-facing change?

no

How was this patch tested?

By existing binary*.sql's results

Was this patch authored or co-authored using generative AI tooling?

no

[yaooqinn]

cc @cloud-fan @dongjoon-hyun @HyukjinKwon @LuciferYang thanks

[LuciferYang]

Is this the function that should be deleted in #42184?

[yaooqinn]

Sorry, I can not answer your question since I wasn't there.

[LuciferYang]

both org.apache.spark.sql.catalyst.util.StringUtils and getHexString are public, should we keep them?

[yaooqinn]

The catalyst package is private by contract

[yaooqinn]

Thank you @HyukjinKwon , merged to master