Separate hash aggregate finalization into its own operator

[benjaminwinger]

This fixes the data race I mentioned in #4906. It's a little difficult to rigorously test since I was having a hard time reproducing it, but moving the finalization into a separate operator should guarantee that all threads running HashAggregate operator tasks finish before finalization starts.

I think this may fix the issue in #4903, but I'm not positive that it's the same issue.

[codecov]

Codecov Report

Attention: Patch coverage is 97.29730% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.52%. Comparing base (cf860af) to head (35c4b2d).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...lude/processor/operator/aggregate/hash_aggregate.h	94.44%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4913   +/-   ##
=======================================
  Coverage   86.51%   86.52%           
=======================================
  Files        1403     1403           
  Lines       60665    60686   +21     
  Branches     7461     7466    +5     
=======================================
+ Hits        52484    52507   +23     
+ Misses       8011     8010    -1     
+ Partials      170      169    -1     

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[github-actions]

Benchmark Result

Master commit hash: cf860af7a6f8be5c0d9754c842946b32264d15cf
Branch commit hash: 837e0cc1b33205d50354cdab96b3217c2f57ac45

Query Group	Query Name	Mean Time - Commit (ms)	Mean Time - Master (ms)	Diff
aggregation	q24	724.67	714.55	10.12 (1.42%)
aggregation	q28	6398.28	6375.88	22.40 (0.35%)
filter	q14	128.98	119.73	9.26 (7.73%)
filter	q15	125.02	116.20	8.82 (7.59%)
filter	q16	305.26	298.32	6.93 (2.32%)
filter	q17	446.61	442.95	3.66 (0.83%)
filter	q18	1901.98	1958.85	-56.87 (-2.90%)
filter	zonemap-node	90.11	80.49	9.62 (11.95%)
filter	zonemap-node-lhs-cast	90.55	80.42	10.14 (12.60%)
filter	zonemap-node-null	91.52	80.19	11.33 (14.13%)
filter	zonemap-rel	5635.69	5583.15	52.54 (0.94%)
fixed_size_expr_evaluator	q07	570.13	563.21	6.91 (1.23%)
fixed_size_expr_evaluator	q08	800.42	796.22	4.19 (0.53%)
fixed_size_expr_evaluator	q09	801.35	793.83	7.52 (0.95%)
fixed_size_expr_evaluator	q10	237.60	228.52	9.08 (3.97%)
fixed_size_expr_evaluator	q11	229.16	220.85	8.30 (3.76%)
fixed_size_expr_evaluator	q12	226.54	218.59	7.95 (3.64%)
fixed_size_expr_evaluator	q13	1449.95	1455.68	-5.73 (-0.39%)
fixed_size_seq_scan	q23	110.59	103.69	6.90 (6.65%)
join	q29	758.73	708.82	49.91 (7.04%)
join	q30	9933.00	10144.89	-211.89 (-2.09%)
join	q31	7.38	7.93	-0.55 (-6.98%)
join	SelectiveTwoHopJoin	54.69	58.89	-4.20 (-7.13%)
ldbc_snb_ic	q35	2663.71	2682.28	-18.57 (-0.69%)
ldbc_snb_ic	q36	468.50	448.07	20.43 (4.56%)
ldbc_snb_is	q32	6.02	6.61	-0.58 (-8.83%)
ldbc_snb_is	q33	15.44	14.27	1.16 (8.15%)
ldbc_snb_is	q34	1.19	1.15	0.04 (3.09%)
multi-rel	multi-rel-large-scan	1324.01	1321.16	2.85 (0.22%)
multi-rel	multi-rel-lookup	45.31	30.54	14.78 (48.40%)
multi-rel	multi-rel-small-scan	65.89	104.66	-38.77 (-37.05%)
order_by	q25	132.41	120.56	11.86 (9.84%)
order_by	q26	457.28	445.27	12.01 (2.70%)
order_by	q27	1415.42	1406.15	9.28 (0.66%)
recursive_join	recursive-join-bidirection	293.46	289.32	4.14 (1.43%)
recursive_join	recursive-join-dense	7334.84	7345.79	-10.95 (-0.15%)
recursive_join	recursive-join-path	24444.58	24144.04	300.54 (1.24%)
recursive_join	recursive-join-sparse	1058.26	1051.52	6.74 (0.64%)
recursive_join	recursive-join-trail	7340.25	7326.78	13.48 (0.18%)
scan_after_filter	q01	172.45	165.35	7.10 (4.29%)
scan_after_filter	q02	158.87	148.69	10.18 (6.85%)
shortest_path_ldbc100	q37	96.54	99.21	-2.68 (-2.70%)
shortest_path_ldbc100	q38	384.99	366.94	18.05 (4.92%)
shortest_path_ldbc100	q39	65.57	66.71	-1.14 (-1.71%)
shortest_path_ldbc100	q40	449.63	463.08	-13.46 (-2.91%)
var_size_expr_evaluator	q03	2069.50	2133.67	-64.17 (-3.01%)
var_size_expr_evaluator	q04	2247.14	2229.90	17.25 (0.77%)
var_size_expr_evaluator	q05	2630.26	2612.23	18.03 (0.69%)
var_size_expr_evaluator	q06	1343.83	1320.33	23.50 (1.78%)
var_size_seq_scan	q19	1458.23	1439.94	18.29 (1.27%)
var_size_seq_scan	q20	2484.80	2473.11	11.70 (0.47%)
var_size_seq_scan	q21	2328.46	2296.57	31.89 (1.39%)
var_size_seq_scan	q22	126.68	124.49	2.18 (1.75%)

[ray6080]

Looks good! Thanks!