chore: remove deprecated horses, clubs, officials, and persons services

- Deleted obsolete modules related to horses, clubs, officials, and persons services, including their configurations, build files, and database provisioning scripts.
- Cleaned up associated references in the project structure (e.g., `settings.gradle.kts`).
- Removed unused database tables and Spring beans related to these domains.

Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>

backend/services/identity/identity-service/build.gradle.kts

@@ -0,0 +1,28 @@
+plugins {
+  alias(libs.plugins.kotlinJvm)
+  alias(libs.plugins.kotlinSpring)
+  alias(libs.plugins.spring.boot)
+  alias(libs.plugins.spring.dependencyManagement)
+}
+
+springBoot {
+  mainClass.set("at.mocode.identity.service.IdentityServiceApplicationKt")
+}
+
+dependencies {
+  implementation(projects.platform.platformDependencies)
+  implementation(projects.core.coreDomain)
+  implementation(projects.core.coreUtils)
+  implementation(projects.backend.services.identity.identityDomain)
+  implementation(projects.backend.services.identity.identityInfrastructure)
+
+  implementation(libs.spring.boot.starter.web)
+  implementation(libs.spring.boot.starter.validation)
+  implementation(libs.spring.boot.starter.security)
+  implementation(libs.spring.boot.starter.oauth2.resource.server)
+
+  implementation(libs.exposed.core)
+  implementation(libs.exposed.jdbc)
+  implementation(libs.hikari.cp)
+  runtimeOnly(libs.postgresql.driver)
+}