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/channelserver/repo_guild_subsystems_test.go

@@ -98,7 +98,7 @@ func TestRolloverDailyRP_Idempotent(t *testing.T) {
 	defer TeardownTestDB(t, db)
 
 	userID := CreateTestUser(t, db, "idem_rollover_user")
-	charID := CreateTestCharacter(t, db, userID, "Idem_Rollover_Leader")
+	charID := CreateTestCharacter(t, db, userID, "IdemRollLeader")
 	guildID := CreateTestGuild(t, db, charID, "Idem_Rollover_Guild")
 	repo := NewGuildRepository(db)