Remove dead publishing and release-notes buildSrc code

Two categories of dead code, both confirmed via exhaustive grep across
all workflows/docs/build files -- nothing invokes any of it, old CI or new:

- ArtifactoryPlugin, PublishArtifactsPlugin, SpringNexusPublishPlugin,
  and the tasks/dependencies that only existed to support them
  (deployArtifacts, finalizeDeployArtifacts, org.jfrog.buildinfo,
  io.github.gradle-nexus, and the already-unused io.codearte
  nexus-staging-plugin). Deploys go through publishAllPublicationsToLocalRepository
  plus ensure-artifacts instead.
- GitHubMilestonePlugin/GitHubReleasePlugin/GitHubChangelogPlugin and
  their DTOs/API classes -- a legacy Gradle-task-based release-notes/
  GitHub-release mechanism already superseded by perform-release's
  GH-Action-based approach (github-changelog-generator +
  publish-release-notes), which itself was removed from ci.yml along
  with the rest of release scheduling/launching.

Also removes MavenBomPlugin (io.spring.convention.bom), which nothing
in this project applies -- the dependencies module uses plain
java-platform instead -- and its now-pointless TestKit sample fixture.

Author: jzheaux

build.gradle

@@ -6,9 +6,7 @@ buildscript {
     dependencies {
         classpath "com.github.ben-manes:gradle-versions-plugin:0.53.0"
         classpath "io.spring.gradle:dependency-management-plugin:1.1.7"
-        classpath "org.jfrog.buildinfo:build-info-extractor-gradle:4.34.2"
         classpath 'org.hidetake:gradle-ssh-plugin:2.10.1'
-        classpath 'io.codearte.gradle.nexus:gradle-nexus-staging-plugin:0.30.0'
         classpath "io.spring.javaformat:spring-javaformat-gradle-plugin:$springJavaformatVersion"
     }
 }
@@ -33,10 +31,6 @@ description = "Spring LDAP"
 
 ext.coreModules = subprojects.findAll { p-> (!p.name.contains("test") && !p.name.contains("sample") && !p.name.contains("sandbox")) || p.name.contains("spring-ldap-test") }
 
-configure(subprojects - coreModules) {
-	tasks.findByPath("publishArtifacts")?.enabled = false
-}
-
 nohttp {
 	source.exclude "buildSrc/build/**"
 }

buildSrc/build.gradle

@@ -49,18 +49,6 @@ gradlePlugin {
             id = "org.springframework.security.sagan"
             implementationClass = "org.springframework.gradle.sagan.SaganPlugin"
         }
-        githubMilestone {
-            id = "org.springframework.github.milestone"
-            implementationClass = "org.springframework.gradle.github.milestones.GitHubMilestonePlugin"
-        }
-        githubChangelog {
-            id = "org.springframework.github.changelog"
-            implementationClass = "org.springframework.gradle.github.changelog.GitHubChangelogPlugin"
-        }
-        githubRelease {
-            id = "org.springframework.github.release"
-            implementationClass = "org.springframework.gradle.github.release.GitHubReleasePlugin"
-        }
         s101 {
             id = "s101"
             implementationClass = "s101.S101Plugin"
@@ -81,7 +69,6 @@ dependencies {
     implementation 'org.yaml:snakeyaml:1.33'
     implementation localGroovy()
 
-    implementation 'io.github.gradle-nexus:publish-plugin:2.0.0'
     implementation 'io.projectreactor:reactor-core:3.8.6'
     implementation ('org.gretty:gretty:5.0.2') {
         exclude group: 'org.springframework.boot', module: 'spring-boot-loader-tools'
@@ -95,7 +82,6 @@ dependencies {
     implementation 'net.sourceforge.htmlunit:htmlunit:2.70.0'
     implementation 'org.asciidoctor:asciidoctor-gradle-jvm:4.0.5'
     implementation 'org.hidetake:gradle-ssh-plugin:2.10.1'
-    implementation 'org.jfrog.buildinfo:build-info-extractor-gradle:4.34.2'
     implementation 'org.springframework:spring-core:6.2.19'
     implementation 'org.sonarsource.scanner.gradle:sonarqube-gradle-plugin:7.1.0.6387'
 

buildSrc/src/main/groovy/io/spring/gradle/convention/ArtifactoryPlugin.groovy

@@ -21,7 +21,6 @@ import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.plugins.BasePlugin
 import org.gradle.api.plugins.PluginManager
-import org.springframework.gradle.maven.SpringNexusPublishPlugin
 
 class RootProjectPlugin implements Plugin<Project> {
 
@@ -31,7 +30,6 @@ class RootProjectPlugin implements Plugin<Project> {
 		pluginManager.apply(BasePlugin)
 		pluginManager.apply(SchemaPlugin)
 		pluginManager.apply(NoHttpPlugin)
-		pluginManager.apply(SpringNexusPublishPlugin)
 		pluginManager.apply("org.sonarqube")
 
 		project.repositories.mavenCentral()
@@ -49,11 +47,6 @@ class RootProjectPlugin implements Plugin<Project> {
 				property "sonar.links.scm_dev", "https://github.com/spring-projects/${projectName}.git"
 			}
 		}
-
-		def finalizeDeployArtifacts = project.task("finalizeDeployArtifacts")
-		if (Utils.isRelease(project) && project.hasProperty("ossrhUsername")) {
-			finalizeDeployArtifacts.dependsOn project.tasks.closeAndReleaseOssrhStagingRepository
-		}
 	}
 
 }

buildSrc/src/main/groovy/io/spring/gradle/convention/MavenBomPlugin.groovy

@@ -35,12 +35,6 @@ class SpringModulePlugin extends AbstractSpringJavaPlugin {
 		pluginManager.apply(SpringMavenPlugin.class);
 		pluginManager.apply("io.spring.convention.jacoco");
 
-		def deployArtifacts = project.task("deployArtifacts")
-		deployArtifacts.group = 'Deploy tasks'
-		deployArtifacts.description = "Deploys the artifacts to either Artifactory or Maven Central"
-		if (!Utils.isRelease(project)) {
-			deployArtifacts.dependsOn project.tasks.artifactoryPublish
-		}
 		project.tasks.withType(Jar) {
 			from(project.rootProject.files('LICENSE.txt')) {
 				into('META-INF')