2.0 removals: LegacyRow, connectionless execution, close_with_result

2.0 removals: LegacyRow, connectionless execution, close_with_result

in order to remove LegacyRow / LegacyResult, we have
to also lose close_with_result, which connectionless
execution relies upon.

also includes a new profiles.txt file that's all against
py310, as that's what CI is on now.  some result counts
changed by one function call which was enough to fail the
low-count result tests.

Replaces Connectable as the common interface between
Connection and Engine with EngineEventsTarget.  Engine
is no longer Connectable.  Connection and MockConnection
still are.

References: #7257
Change-Id: Iad5eba0313836d347e65490349a22b061356896a