Plan: Make linux_packaging independent of ci_build

Problem:

• linux_packaging job depends on ci_build
• When only packaging files change (packagingChanged=true but source=false), ci_build is skipped
• This causes linux_packaging to also be skipped due to the dependency

Solution:

• Update .github/workflows/linux-ci.yml to remove ci_build dependency from linux_packaging
• Update .github/actions/test/linux-packaging/action.yml to do its own build instead of downloading artifacts
• Follow the pattern used by windows-packaging-reusable.yml which does its own build
• Ensure linux_packaging only depends on changes job
• Update path-filters to include Linux packaging paths for consistency
• Fix YAML linting issues (trailing spaces)
• Code review passed with no issues
• Security scan passed with no issues
• Address reviewer feedback: combine build and packaging into single step
• Add instructions documenting the build/packaging pattern
• Fix missing packaging dependencies (fpm) by adding Start-PSBootstrap
• Remove redundant Sync-PSTags calls (already done by Invoke-CIInstall)
• Remove -PSModuleRestore parameter (now enabled by default)

Changes Made:

1. Removed ci_build from linux_packaging job dependencies in linux-ci.yml
2. Updated linux-packaging action to:
   • Remove artifact download and extraction steps (43 lines removed)
   • Add combined build and package step using Start-PSBuild + Invoke-CIFinish
   • Run build and packaging in same step to maintain PSOptions in memory
   • Add Start-PSBootstrap -Scenario Package to install packaging dependencies (fpm, rpmbuild, etc.)
   • Remove redundant Sync-PSTags calls (already handled by Invoke-CIInstall)
   • Remove -PSModuleRestore parameter (now default behavior)
   • Simplified from 111 lines to 59 lines
3. The action now follows the same pattern as Windows packaging: bootstrap, then build+package
4. Updated path-filters to include:
   • .github/workflows/linux-ci.yml (was only including windows-ci.yml)
   • test/packaging/linux/ (was only including windows tests)
5. Fixed trailing spaces in path-filters YAML file
6. Added comprehensive instruction file documenting the build/packaging pattern with correct default behavior

Result:
The linux_packaging job will now run whenever packagingChanged=true, regardless of whether source=true or ci_build runs. This matches the behavior of the Windows packaging workflow.

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