[statspro] Restart drop db

[max-hoffman]

Quick fix for at least one of the problems in #8345.

The specific example fails because the restart function refreshes the stats database instance, but does not reload the stats contained within. So the contents in memory did not track the contents on disk. This was only noticeable when restart and read were called within the same shell context.

[coffeegoddd]

@max-hoffman DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
205249f	ok	5937457

version	total_tests
205249f	5937457

correctness_percentage
100.0

[coffeegoddd]

@max-hoffman DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
840fe90	ok	5937457

version	total_tests
840fe90	5937457

correctness_percentage
100.0

[nicktobey]

Can you add a bit more context in the description? Why was this causing a restart to drop the stats db?

[max-hoffman]

Updated comment. We were initializing the stats DB but not the in-memory contents.