Remove no-op AutoIncrement statement

[nicktobey]

A simple cleanup: this line always errors, but the error isn't being checked. It effectively does nothing and isn't needed because:

• the auto increment state is automatically updated by the AutoIncrement node in the plan tree
  -as long as the auto_increment as long as w.aiSet is true, the correct auto_increment value will be read from the AutoIncrementTracker.

[coffeegoddd]

@nicktobey DOLT

read_tests	from_latency	to_latency	percent_change
covering_index_scan	2.3	2.3	0.0
groupby_scan	142.39	144.97	1.81
index_join	1.96	1.96	0.0
index_join_scan	1.34	1.34	0.0
index_scan	219.36	219.36	0.0
oltp_point_select	0.25	0.25	0.0
oltp_read_only	5.09	5.09	0.0
select_random_points	0.51	0.51	0.0
select_random_ranges	0.65	0.64	-1.54
table_scan	204.11	207.82	1.82
types_table_scan	467.3	467.3	0.0

write_tests	from_latency	to_latency	percent_change
oltp_delete_insert	6.21	6.21	0.0
oltp_insert	3.13	3.13	0.0
oltp_read_write	11.24	11.24	0.0
oltp_update_index	3.3	3.3	0.0
oltp_update_non_index	3.02	3.02	0.0
oltp_write_only	6.32	6.32	0.0
types_delete_insert	6.79	6.79	0.0

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
d68dad9	ok	5937471

version	total_tests
d68dad9	5937471

correctness_percentage
100.0

[coffeegoddd]

@nicktobey DOLT

test_name	from_latency_p95	to_latency_p95	percent_change
tpcc-scale-factor-1	45.79	46.63	1.83

test_name	from_server_name	from_server_version	from_tps	to_server_name	to_server_version	to_tps	percent_change
tpcc-scale-factor-1	dolt	1276689	52.86	dolt	d68dad9	52.73	-0.25

[jycor]

LGTM