[Enhancement] add limit operator before union gather

[stdpain]

Why I'm doing:

baseline:

mysql>   select  to_bitmap(1) FROM TABLE(generate_series(0, 655350)) union all select bitmap_agg(lo_orderkey) from lineorder group by lo_linenumber limit 1;
+--------------+
| to_bitmap(1) |
+--------------+
| NULL         |
+--------------+
1 row in set (7.42 sec)

patched:

mysql> select  to_bitmap(1) FROM TABLE(generate_series(0, 655350)) union all select bitmap_agg(lo_orderkey) from lineorder group by lo_linenumber limit 1;
+--------------+
| to_bitmap(1) |
+--------------+
| NULL         |
+--------------+
1 row in set (0.04 sec)

What I'm doing:

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
  • 3.4
  • 3.3
  • 3.2
  • 3.1
  • 3.0

[github-actions]

[FE Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[Java-Extensions Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[BE Incremental Coverage Report]

✅ pass : 4 / 4 (100.00%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	be/src/exec/union_node.cpp	4	4	100.00%	[]

[github-actions]

@Mergifyio backport branch-3.4

[github-actions]

@Mergifyio backport branch-3.3

[mergify]

backport branch-3.4

✅ Backports have been created

• #53120 [Enhancement] add limit operator before union gather (backport #53102) has been created for branch branch-3.4

[mergify]

backport branch-3.3

✅ Backports have been created

• #53121 [Enhancement] add limit operator before union gather (backport #53102) has been created for branch branch-3.3