Are there any mods that do this?
Not to my knowledge.
I tried going to raceconfig and changing the techtree to minor race for all of them but it doesn't change anything.
Actually, that's the way to do it. I'm not certain as to why that didn't work, but it's likely that you either forgot to start a new game, or edited the wrong file (there are three RaceConfig.xml's, one for the base game, and one for each expansion). However, considering that you found the racial tech trees, the latter is less likely.
In any case, simply replacing the original tech tree with the minor one for each race is not enough. Each race has a set of starting techs, most of which aren't in the minor race tech tree. If you don't correct this, then some of the races will be unable to compete, because they don't have any factories, labs, and so on, at the start of the game. All you need to do is to replace the current starting techs for each race with the following: