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/0012_guild_invites.sql

@@ -2,7 +2,7 @@
 -- player-initiated applications. This gives each invitation a real serial PK
 -- so the client's InvitationID field can map to an actual database row
 -- instead of being aliased to the character ID.
-CREATE TABLE guild_invites (
+CREATE TABLE IF NOT EXISTS guild_invites (
     id           serial PRIMARY KEY,
     guild_id     integer REFERENCES guilds(id),
     character_id integer REFERENCES characters(id),