T6961: package-build: Fix kea build race condition

[MattKobayashi]

Change Summary

Fix a race condition in the kea package build process.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

https://vyos.dev/T6961

Component(s) name

package-build (kea)

Proposed changes

Because the package.toml file for the kea package doesn't specify a build command, it defaults to running dpkg-buildpackage -uc -us -tc -F against the cloned git repo. This is a problem because, by default, dpkg-buildpackage runs tasks in parallel (the limit is defined as auto, but seems to be based off the number of processors the system has), and there's a component being compiled in kea that other make tasks rely on, but ends up sometimes not being built in time for the dependent task to run successfully.

This PR adds a build command to kea's package.toml that specifies the additional argument -j 1 to the original dpkg-buildpackage command, which reverts dpkg-buildpackage's behaviour to serial execution of tasks.

How to test

(using the modified `package.toml`)
git clone https://github.com/vyos/vyos-build
cd vyos-build/scripts/package-build/kea
./build.py

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[github-actions]

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No issues in PR Title / Commit Title

[sever-sever]

The logic is

1. it tries to check if build_cmd exists; if not command, it tries to build source + binary
2. If sources fail, it tries to build binaries only

https://github.com/vyos/vyos-build/blob/c1f9fc6a6d387648e91a74a72b3488c42a6b897a/scripts/package-build/build.py#L117C1-L126C65

The similar logic as for Jenkins

vyos-build/vars/cloneAndBuild.groovy

Lines 67 to 71 in c1f9fc6

	sh 'dpkg-buildpackage -uc -us -tc -F'
	} catch (e) {
	print "Source packages build failed, ignoring - building binaries only"
	currentBuild.result = 'SUCCESS'
	sh 'dpkg-buildpackage -uc -us -tc -b'