Remove obsolete mods which are maintained in other repos

[cainiaowu]

Fix #20326.

Remove obsoleted Arcana and PK Rebalancing mods as both authors expressed that they want them removed from master.

They are maintained in following repo:

Arcana: https://github.com/chaosvolt/cdda-arcana-mod

Pisskop's Rebalancing: https://github.com/pisskop/PKs_Rebalancing

See also

pisskop/PKs_Rebalancing#30

cataclysmbnteam#22

[Leland]

What would this do to old saves?

Also see: #20129

[Cyrano7]

Maybe just add "obsolete": true to Arcana for now? Maybe some legacy stuff could be dropped after or right before a stable release?

[pisskop]

it is 30k lines removed ...

[cainiaowu]

@Cyrano7 They have been "obsolete": true for almost a year now, which means they are invisible to new gamer for almost a year, unless someone has a savefile that doesnt break on load with these mods on in newest experimental (which doesnt exist, see chatsvolts issue), we can drop these two mods just fine.

[kevingranade]

10 and 11 months of obsoletion, seems like plenty of notice.