fix(ksqldb-client-api): fix describeConnector issued query

[bas-velthuizen]

This PR fixes issue #10150 Also, the unit test is made more strict to test for correct query

Description

The ClientImpl.describeConnector method does not add quotes around the connector name. This fix adds the quotes.

Testing done

The unit test has been expanded to verify the issued query.

Reviewer checklist

• [ ] Ensure docs are updated if necessary. (eg. if a user visible feature is being added or changed).
• [ ] Ensure relevant issues are linked (description should include text like "Fixes #")
• [ ] Do these changes have compatibility implications for rollback? If so, ensure that the ksql command version is bumped.

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[bas-velthuizen-alfen]

Jenkins seems to be failing, but I cannot get the current master of the repo to build on my own system, so I cannot check that. With version 7.5.2 as a base, the build did succeed locally.