Does the supplication in the form of "O Allah, You are the Master, and I am Your handmaiden, and I possess no control over my affairs, so choose for me and do not let me choose, and do with me as You will" contradict the necessity of certainty and resolve in supplication and the prohibition of conditioning it upon Your will?

The characteristic of a supplication that includes seeking Allah's guidance (Istikharah) to achieve what is best is not considered suspending the supplication on Allah's will, which is prohibited. This is because a person does not know what is truly beneficial for them, and they might ask for something that would lead to their ruin, as confirmed by Allah's words: "And man supplicates for evil as he supplicates for good, and man is ever hasty." However, there is no harm in asking for a specific thing when you perceive goodness in it, following the example of the prophets who asked Allah for what they desired.