[4.x] DefaultSslEngineFactoryWithClientAuthIT and DefaultSslEngineFactoryWithClientAuthIT wrongly configuring scylla

[fruch]

Those test enable client encryption on scylla end, but not using a specific certificate, and scylla defaults to non-existing one:

12:18:00.008 [Exec Stream Pumper] ERROR c.d.o.d.api.testinfra.ccm.CcmBridge - ccmout> ERROR 2023-06-04 12:17:59,753 [shard 0] init - Startup failed: std::_Nested_exception<std::runtime_error> (Could not read certificate file /tmp/ccm16330012472966843243/ccm_1/node1/conf/scylla.crt): std::filesystem::__cxx11::filesystem_error (error system:2, filesystem error: open failed: No such file or directory [/tmp/ccm16330012472966843243/ccm_1/node1/conf/scylla.crt])