fix(tests): fix three CI failures on develop

- alliance recruiting default: change DEFAULT true → false in both
  0001_init.sql and 0004_alliance_recruiting.sql; new alliances should
  not be open for recruitment by default (TestSetAllianceRecruiting)
- guild_invites migration: add IF NOT EXISTS so re-running migrations
  on an existing DB does not fail with "relation already exists"
  (TestMigrateExistingDBWithoutSchemaVersion)
- test character name: shorten "Idem_Rollover_Leader" (19 chars) to
  "IdemRollLeader" to fit the VARCHAR(15) constraint
  (TestRolloverDailyRP_Idempotent)

server/migrations/sql/0004_alliance_recruiting.sql

@@ -1 +1 @@
-ALTER TABLE public.guild_alliances ADD COLUMN IF NOT EXISTS recruiting boolean NOT NULL DEFAULT true;
+ALTER TABLE public.guild_alliances ADD COLUMN IF NOT EXISTS recruiting boolean NOT NULL DEFAULT false;