Fix druid shapeshifting mana bug, paladin bonus healing bug, "City" instance label + res exploit

All these fixes have been tested and working on my test server (newest main branch commit)

Since Holy Light and Flash of Light are handled in their own, they need to have bonus healing added just like other healing does in SPELL_EFFECT_HEAL.

Druid  bug appeared since previously the case to set max mana was skipped, but post https://github.com/cmangos/mangos-classic/commit/25432f1f378a2ebc03e56e38637ceab4303adafe it was set, thus setting druid mana to base mana when they shifted back to normal form

Multiple instances (including BRD, MC, DM and more) were labelled "City" ever since https://github.com/cmangos/mangos-classic/commit/6251b3b3eb25a7e1f8cf8eb99e0653d6f84e6caa
This caused the game to not find any graveyards to teleport the players ghost to, thus meaning the ghost spawned at the player and you could essentially die and move in ghost form to the end of an instance. Fix accredited to https://github.com/Neotmiren for the comment at the bottom of the commit.

First 2 fixes are at second commit (sorry for not putting each fix in its own commit, I had a few problems with the fork) and the last one is in the 4th commit.