[Master] Improve / Fix Hero Academy

[yelnats_24]

Here is the thread:…

@TheEyes

Also:

• Lower the cost and training time of HA7 (trainer hero training) and increase the odds of higher-rarity trainer heroes, until it’s worth using at some point, likely for training level 60+ heroes
• Lower the cost and time for all troop training options (except HA9) so it doesn’t take two decades to train troops to high levels.