perf: tune limit on dynamodb.Query in get-views-lambda

[jcserv]

The DynamoDB Query API "... will read up to the maximum number of items set (if using the Limit parameter) or a maximum of 1 MB of data".

The current limit of 250 was chosen arbitrarily, but since the item size is pretty small (Avg: 24.5 bytes), this could be increased.

Acceptance Criteria:

• Do perf testing, determine upper limit of Query
• Tweak Query to use discovered limit