[SPARK-46070][SQL] Compile regex pattern in SparkDateTimeUtils.getZoneId outside the hot loop

[tanelk]

What changes were proposed in this pull request?

Compile the regex patterns used in SparkDateTimeUtils.getZoneId outside of the method, that can be called for each dataset row..

Why are the changes needed?

String.replaceFirst internally does Pattern.compile(regex).matcher(this).replaceFirst(replacement). Pattern.compile is very expensive method, that should not be called in a loop.

When using method like from_utc_timestamp with non-literal timezone, the SparkDateTimeUtils.getZoneId is called for each loop. In one of my usecases adding from_utc_timestamp increased the runtime from 15min to 6h.

Does this PR introduce any user-facing change?

Performance improvement.

How was this patch tested?

Existing UTs

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

No

[MaxGekk]

Could you assign more specific names like:

Suggested change

	final val tzRegexShort = Pattern.compile("(\\+|\\-)(\\d):")
	final val tzRegexLong = Pattern.compile("(\\+|\\-)(\\d\\d):(\\d)$")
	final val singleHourTz = Pattern.compile("(\\+|\\-)(\\d):")
	final val singleMinuteTz = Pattern.compile("(\\+|\\-)(\\d\\d):(\\d)$")

Short and Long term slightly confuses sine they could not reflect actual tz for example:
Long: 08:3
Short: 8:30:00

[MaxGekk]

Waiting for CI.

[MaxGekk]

+1, LGTM. Merging to master.
Thank you, @tanelk.