[Enhancement]prefetch agg_hash_set

[zombee0]

Why I'm doing:

What I'm doing:

sql	old	new	imporvement
select count (distinct lo_linenumber) from lineorder_flat;	0.70	0.72	0 as expected
SELECT COUNT (DISTINCT s_name) FROM lineorder_flat;	15.83	13.58	16%
select count (distinct lo_suppkey) from lineorder_flat;	2.36	1.81	30%
SELECT COUNT (DISTINCT lo_suppkey) FROM lineorder_flat group by lo_linenumber;	6.23	4.21	48%
SELECT COUNT (DISTINCT lo_suppkey) FROM lineorder_flat group by lo_linenumber, lo_orderpriority;	34.45	32.87	4.8%
SELECT COUNT (DISTINCT lo_suppkey) FROM lineorder_flat group by lo_orderpriority;	26.65	22.27	19%

Fixes #issue

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 3.3
  • 3.2
  • 3.1
  • 3.0
  • 2.5

[stdpain]

prefetch may cause performance degradation. refer #4856

[zombee0]

prefetch may cause performance degradation. refer #4856

yes, there is a prefetch threshold.

[github-actions]

[FE Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[BE Incremental Coverage Report]

✅ pass : 118 / 126 (93.65%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	be/src/exec/aggregate/agg_hash_set.h	118	126	93.65%	[178, 259, 278, 363, 433, 459, 575, 698]

[LiShuMing]

Good~