[C++][FlightRPC][ODBC] Reuse ODBC connections across tests

[justing-bq]

Describe the enhancement requested

Currently our tests are connecting/disconnecting for each test fixure. But connecting/disconnecting too many times can cause tests to crash on Linux. We can limit the number of connection attempts if we reuse the same ODBC connections where possible across the entire test suite.

Component(s)

C++, FlightRPC

[kou]

Issue resolved by pull request 49784
#49784