Tests | Improve ConnectivityTest

[JRahnama]

Based on issue #1196, I have made some improvements to that class.

I have changed the specific test to not throw an exception instead it checks for Assert.Throws
I also changed the timer to use stopwatch and TimeSpan instead of capturing current date and calculate the elapsed time after.

In general I applied the C#9 features to the entire class.

@Wraith2 can you check this with the issue as well. I just want to distinguish if this is a driver issue or test implementation.

Thanks

[Wraith2]

This compiles, runs and fails in the same way as the original for me:

 Event Trace (<prov.DbConnectionHelper.ConnectionString_Set|API> 31, 'Data Source=tcp:WRAITH\SQL2017;Initial Catalog=DoesNotExist0982532435423;Integrated Security=False;User ID=testuser;Pooling=False;Connect Timeout=1').
 Event ScopeEnter (SqlConnection.Open | API | Correlation | Object Id 31, Activity Id 1266df57-f44f-4011-800d-fb051a5e6713:1).
 Event CorrelationTrace (SqlConnection.Open | API | Correlation | Object Id 31, Activity Id 1266df57-f44f-4011-800d-fb051a5e6713:1).
 Event Trace (<sc.SqlConfigurableRetryLogicManager.ConnectionProvider|INFO> Requested the ConnectionProvider value.).
 Event Trace (TdsParserStateObjectFactory.CreateTdsParserStateObject | Info | AppContext switch 'Switch.Microsoft.Data.SqlClient.UseManagedNetworkingOnWindows' not enabled, native networking implementation will be used.).
 Event Trace (TdsParser.Connect | SEC | Connection Object Id 6, Authentication Mode: SqlPassword).
 Event Trace (<sc.TdsParser.Connect|SEC> Sending prelogin handshake).
 Event Trace (<sc.TdsParser.SendPreLoginHandshake|INFO> ClientConnectionID 4a9f1c36-bcb1-4c25-a653-6e31a6babd51, ActivityID 46fc6e74-042f-4a84-9023-4367968f506e:2).
 Event Trace (<sc.TdsParser.Connect|SEC> Consuming prelogin handshake).
 Event Trace (SqlError.ctor | ERR | Info Number 4060, Error State 1, Error Class 11, Error Message 'Cannot open database "DoesNotExist0982532435423" requested by the login. The login failed.', Procedure '', Line Number 1).
 Event Trace (SqlError.ctor | ERR | Info Number 18456, Error State 1, Error Class 14, Error Message 'Login failed for user 'testuser'.', Procedure '', Line Number 1).
 Event Trace (<sc|ActiveDirectoryAuthenticationTimeoutRetryHelper|GetCachedToken|Info>Retrieved cached token null.).
 Event Trace (<sc|ActiveDirectoryAuthenticationTimeoutRetryHelper|CheckCanRetry|Error>Cannot retry when cached token is null.).
 Event Trace (<sc.SqlInternalConnectionTds.LoginFailure|RES|CPOOL> 6).
 Event ScopeLeave (Exit Scope 1).
 Event ScopeEnter (SqlConnection.Open | API | Correlation | Object Id 31, Activity Id 46fc6e74-042f-4a84-9023-4367968f506e:2).
 Event CorrelationTrace (SqlConnection.Open | API | Correlation | Object Id 31, Activity Id 46fc6e74-042f-4a84-9023-4367968f506e:2).
 Event Trace (TdsParserStateObjectFactory.CreateTdsParserStateObject | Info | AppContext switch 'Switch.Microsoft.Data.SqlClient.UseManagedNetworkingOnWindows' not enabled, native networking implementation will be used.).
 Event Trace (TdsParser.Connect | SEC | Connection Object Id 7, Authentication Mode: SqlPassword).
 Event Trace (<sc.TdsParser.Connect|SEC> Sending prelogin handshake).
 Event Trace (<sc.TdsParser.SendPreLoginHandshake|INFO> ClientConnectionID 59c3b6c3-5ca1-453c-bc6b-da8449230ccf, ActivityID 39379a75-50db-487e-9c2c-6ff80a77114a:3).
 Event Trace (<sc.TdsParser.Connect|SEC> Consuming prelogin handshake).
 Event Trace (SqlError.ctor | ERR | Info Number 4060, Error State 1, Error Class 11, Error Message 'Cannot open database "DoesNotExist0982532435423" requested by the login. The login failed.', Procedure '', Line Number 1).
 Event Trace (SqlError.ctor | ERR | Info Number 18456, Error State 1, Error Class 14, Error Message 'Login failed for user 'testuser'.', Procedure '', Line Number 1).
 Event Trace (<sc|ActiveDirectoryAuthenticationTimeoutRetryHelper|GetCachedToken|Info>Retrieved cached token null.).
 Event Trace (<sc|ActiveDirectoryAuthenticationTimeoutRetryHelper|CheckCanRetry|Error>Cannot retry when cached token is null.).
 Event Trace (<sc.SqlInternalConnectionTds.LoginFailure|RES|CPOOL> 7).
 Event ScopeLeave (Exit Scope 2).
 Event ScopeEnter (SqlConnection.Close | API | Object Id 31).
 Event CorrelationTrace (SqlConnection.Close | API | Correlation | Object Id 31, Activity Id 39379a75-50db-487e-9c2c-6ff80a77114a:3, Client Connection Id 00000000-0000-0000-0000-000000000000).
 Event ScopeLeave (Exit Scope 3).