Test connection function to create an event stream connection

[v-ryotak1]

The test connection that is created when adding a data source to an event stream does not function properly when creating a new connection.

For instance, if a test connection is checked with incorrect data source information, it will be created without error message.

Because of this unexpected behavior, the user cannot verify that the information is incorrect at the time of creation.

If the connection was tested internally and nothing way to check from the user side, the behavior would be the same as it were not checked.

We kindly request that this feature be improved to display the results of the test connection.