Add tests for dolt_statistics

[tbantle22]

GMS: dolthub/go-mysql-server#2762
Dolt: dolthub/dolt#8589

[github-actions]

	Main	PR
covering_index_scan_postgres	436.12/s	436.67/s	+0.1%
index_join_postgres	162.05/s	160.77/s	-0.8%
index_join_scan_postgres	187.19/s	186.55/s	-0.4%
index_scan_postgres	15.07/s	14.98/s	-0.6%
oltp_point_select	2838.94/s	2844.34/s	+0.1%
oltp_read_only	1938.96/s	1912.83/s	-1.4%
select_random_points	120.49/s	119.63/s	-0.8%
select_random_ranges	93.22/s	92.55/s	-0.8%
table_scan_postgres	14.78/s	14.72/s	-0.5%
types_table_scan_postgres	6.95/s	6.92/s	-0.5%

[github-actions]

	Main	PR
Total	42090	42090
Successful	14534	14534
Failures	27556	27556
Partial Successes1	4689	4689

	Main	PR
Successful	34.5308%	34.5308%
Failures	65.4692%	65.4692%

Footnotes

1. These are tests that we're marking as Successful, however they do not match the expected output in some way. This is due to small differences, such as different wording on the error messages, or the column names being incorrect while the data itself is correct. ↩

[zachmu]

LGTM