[ST] Deflake Connector ST weird usernames TLS/SCRAM tests

[henryZrncik]

Type of change

• Bugfix

Description

testConnectScramShaAuthWithWeirdUserName and testConnectTlsAuthWithWeirdUserName in ConectST were using external clients and creating new TestStorage (which was not referencing the same data as the TestStorage instance from test) in helper function testConnectAuthorizationWithWeirdUserName .

• External clients were replaced with internals as the only reason for them was that the internal clients were not available that time
• helper method was replaced with 3 additional steps in each of those method.

Fixes #7608

[Frawless]

/azp run regression

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[henryZrncik]

Azure is okay the fail is unrelated (the problem is currently flaky KafkaRebalance test which is part of another topic/PR).