fix stats functions to include schema

[jycor]

We lookup stats with empty string for schema. Since this is not always the case, we sometimes miss stats.

[coffeegoddd]

@jycor DOLT

read_tests	from_latency	to_latency	percent_change
covering_index_scan	2.3	2.3	0.0
groupby_scan	142.39	142.39	0.0
index_join	1.93	1.93	0.0
index_join_scan	1.32	1.32	0.0
index_scan	219.36	219.36	0.0
oltp_point_select	0.25	0.25	0.0
oltp_read_only	5.0	5.0	0.0
select_random_points	0.51	0.51	0.0
select_random_ranges	0.64	0.64	0.0
table_scan	200.47	200.47	0.0
types_table_scan	467.3	458.96	-1.78

write_tests	from_latency	to_latency	percent_change
oltp_delete_insert	6.09	6.09	0.0
oltp_insert	3.13	3.13	0.0
oltp_read_write	11.24	11.24	0.0
oltp_update_index	3.25	3.3	1.54
oltp_update_non_index	3.02	2.97	-1.66
oltp_write_only	6.21	6.21	0.0
types_delete_insert	6.79	6.79	0.0

[coffeegoddd]

@jycor DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
733c787	ok	5937471

version	total_tests
733c787	5937471

correctness_percentage
100.0

[coffeegoddd]

@jycor DOLT

test_name	from_latency_p95	to_latency_p95	percent_change
tpcc-scale-factor-1	45.79	44.98	-1.77

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	224f93b	52.42	dolt	3d37e25	52.15	-0.52

[coffeegoddd]

@jycor DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
8f4891a	ok	5937471

version	total_tests
8f4891a	5937471

correctness_percentage
100.0

[coffeegoddd]

@jycor DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
f96969e	ok	5937471

version	total_tests
f96969e	5937471

correctness_percentage
100.0

[fulghum]

Looks good, but I think we may want to update the DropDbStats method in GMS to take a schema and then update here.

[coffeegoddd]

@jycor DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
3d37e25	ok	5937471

version	total_tests
3d37e25	5937471

correctness_percentage
100.0

[coffeegoddd]

@jycor DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
9577750	ok	5937471

version	total_tests
9577750	5937471

correctness_percentage
100.0