Large amount of connections can cause performance degradation

[kukgini]

In aca-py 0.7.4, If agent disclose a multi-use invitation for all invitee, When the number of connections increases, the return records of Askar's SCAN_QUERY grow proportionally. As a result, In proportion, the total execution time of connection 1.0 process increases.

[swcurran]

@ianco and @andrewwhitehead -- could you please take a look at this. Is there something we can do about this?

Thanks

[reflectivedevelopment]

See #2116