find-tables: Default value of 1 makes sense for --score-cutoff option

[nj1973]

From find-tables tool documentation (https://github.com/GoogleCloudPlatform/professional-services-data-validator#building-matched-table-lists):
"
Note that our score cutoff default is a 0.8, which was manually tested to be an accurate value. If no matches occur, reduce this value.
"

I believe the expectation from most end users would for table name matching to be case-insensitive but precise regarding the alphanumeric values used.

I think it would make more sense to --score-cutoff default to 1 and let customers reduce the value if they require non-exact matching.

This is low priority.