Add missing endpoint to exception message in ExecuteSql.

[aaronweeden]

Description

The ETL maintenance class ExecuteSql only uses destinationEndpoint, not sourceEndpoint. However, when exceptions are logged, it tries to report the sourceEndpoint. This PR fixes this to instead report the destinationEndpoint.

Tests performed

I ran an SQL query on my port on xdmod-dev that I knew was incorrect, and it reported the following (note that the endpoint is not reported):

xsede.migration-11_0_0p1-11_0_0p2.MapUnknownOodPeople (ETL\Maintenance\ExecuteSql): Error executing SQL Exception: 'SQLSTATE[42S02]: Base table or view not found: 1146 Table 'modw.page_impressions' doesn't exist'

Then I applied the fix, ran it again, and the endpoint is now reported in the exception:

xsede.migration-11_0_0p1-11_0_0p2.MapUnknownOodPeople (ETL\Maintenance\ExecuteSql): Error executing SQL Exception: 'SQLSTATE[42S02]: Base table or view not found: 1146 Table 'modw.page_impressions' doesn't exist' Using DataEndpoint: '('Database with Open OnDemand usage data', class=ETL\DataEndpoint\Mysql, config=datawarehouse, schema=modw_ondemand, host=mysql-dev.ccr.xdmod.org:3306, user=xdmod)'

Checklist:

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