Fix m_requestHostName variable behavior

[airween]

what

This PR fixes the wrong behavior of m_requestHostName transaction variable.

why

Previously, this variable was set when the setRequestHostName() was called, but previously it was initialized in processConnection(). So the last function overwritten the variable, and the previously set value disappeared.

If the connector calls if after processConnection(), then the host field in log entries which generated during processConnection() phase does not contain the necessary value.

The solution was to add a condition which sets the m_requestHostName only if it's empty. Also the correct call to the function setRequestHostName() can be seen in the regression.cc.

This modification does not modify the API.

[sonarcloud]

Quality Gate failed

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E Maintainability Rating on New Code (required ≥ A)

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[airween]

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