No one seems to have answered the question. Perhaps because the answer is so well known. It is an example of a king asking his servant to prepare wine (by mixing with water) and then spilling the water (over him). This tells the servant that he doesnt want his 'services'. Hashem is also telling us by bringing rain that he doesnt want our mitsvot and would rather do without them. Meaning we are not on the madrega to be able to do them and please him.
This goes against the lubavich (and other kiruv) principles to get people to do mitvot. Hashem doesnt want 'everyone's' mitvot only from 'certain' people who are on the madrega.
This question was only put here because of its supplementary which cannot be answered elsewhere at the moment. This has so far not produced any answers and seems to have eluded everyone here. It is quite a long answer having to explain a difficult gemoro with many shittos, some totally against the gemoro and I will do so slowly.
I will first add a chiddush of my own which will go someway to explaining the 'rain'.
The moshol or parable is of a king and his servant. He most likely only had one servant (at a time) who mixed his drinks. Providing a 'downpour' seems like collective 'punishment' or displeasure. It doesnt usually rain just on one succah and not on the next. And also in the other examples of this kind of thing, of hashem expressing his displeasure it is not in a 'collective' way but a private one.
I therefore think although highly unusual and improbable but still possible, that it really refers to when it rained on one succah and not on the next. There are such chasidic tales. That is clear proof that hashem is not interested in your mitsvot.
Although the example I gave on another thread was regarding a person who is not yet ready to learn kabala and does so, the gemoro refers to another example and the poskim like the chayai odom say it refers to that as well.
In the gemoro's example where the early poskim give the same moshol of the king and servant, matters are more serious. There it is a 'private' and 'deadly' sign not a collective one like with rain and although the mishne berura and others tells you what to do about it, basically to learn, daven certain tfillos daily, and good deeds, there is still some arguement if it will save you from death or just make your passage to the next world 'easier'.
To be continued if found to be of interest or if someone at last can find out what I am talking about. I have almost said it.