refactor: extract shared LinuxPackaging utility to eliminate build script duplication

[gdams]

Summary

Extracts all duplicated Gradle build logic from the 16 platform build.gradle files (jdk/jre × alpine/debian/redhat/suse) in both linux/ and linux_new/ into a shared LinuxPackaging utility class in buildSrc.

Problem

Each platform build file contained ~150-230 lines of nearly identical code:

• ~60 lines of boilerplate (plugins, repositories, dependencies, sourceSets, test config)
• ~100 lines of docker build/run/check task logic with only minor parameter differences

This made maintenance painful — any change to the build pattern required updating 16+ files, with inevitable drift and inconsistency.

Solution

A single LinuxPackaging.groovy class in buildSrc provides:

• applyCommonConfig(project) — sets up all shared Gradle configuration
• configure(project, config) — creates packaging and check tasks from a declarative config map

Each platform build file is now ~10 lines:

import org.adoptium.LinuxPackaging

LinuxPackaging.configure(project, [
    imageType    : 'jdk',
    distro       : 'RedHat',
    dockerTag    : 'redhat',
    gpgBuild     : true,
    localBuild   : true,
    extraRunEnvs : ['buildVersion', 'buildLocalFlag'],
    microsoftPkg : true,
    gpgCheck     : true,
    archCheck    : true,
])

Changes

• New: linux/buildSrc/src/main/groovy/org/adoptium/LinuxPackaging.groovy
• New: linux_new/buildSrc/ with ExecHelper.groovy + LinuxPackaging.groovy
• Simplified: All 16 platform build.gradle files + ca-certificates/debian/build.gradle
• Net: -2,967 lines, +207 lines

Compatibility

• All Gradle task names preserved exactly (packageJdkAlpine, checkJdkRedHat, packageJdkrhel, etc.)
• Jenkinsfiles and CI pipelines require no changes
• Verified with ./gradlew tasks on both linux/ and linux_new/

[steelhead31]

Looks good, the code looks much cleaner with this refactor.

[andrew-m-leonard]

looks good