Update mattermost package to expose common helm path override variables that are currently being copy/pasted across uds-bundle.yaml files

[zachariahmiller]

Is your feature request related to a problem? Please describe.

update mattermost package to use the variable override definitions in zarf that have been used via bundle overrides to date so that there is less copy/paste of common variable overrides into bundles definitions Describe alternatives you've considered

(optional) A clear and concise description of any alternative solutions or features you've considered. Additional context

Add any other context or screenshots about the feature request here. https://github.com/defenseunicorns/zarf/pull/2403 https://github.com/defenseunicorns/zarf/issues/2133