Stored procedure netActivityLogEntrySave performance tuning

Description

SP reported to run slowly in customer environment (100ms), when looking at TSQL it seems unnecessary that the MERGE statements for tblActivityLogAssociation runs for inserts and it would be faster to just insert the data directly in this scenario. Especially if this table grows large.

Since activity logs are stored asynchronously this tuning is probably not having any affect on site performance but might make the stored procedure run faster when monitoring database traffic.