Update default limits for get_full_accounts API

[abitmore]

For issue #2165.

New default values:

# For database_api_impl::get_full_accounts to set max accounts to query at once
# api-limit-get-full-accounts = 50

# For database_api_impl::get_full_accounts to set max items to return in the lists
# api-limit-get-full-accounts-lists = 500

The old values were 10 and 100.

TODO:

• update release notes