Mani, that - the term "presales testing" - in the context you describe it is completely meaningless in the USA.
Apparently, you are talking about responding to an RFP ("request for proposal"), right? Then your response is a <u>proposal!!</u>
And if - IF - we are understanding you correctly, then your question might be completely unrelated to software QA/testing, except to the extent that it relates to the <u>section</u> of the proposal dealing with testing. Is that what you mean?
Following that line, it might appear that you are looking for a job description for someone whose sole(?) job is to write the section of a proposal related to testing the proposed solution. Seems a bit narrow to me.