mattermost update to 10.2.0-bb.4

Package Merge Request

Package Changes

https://repo1.dso.mil/big-bang/product/packages/mattermost/-/blob/10.2.0-bb.4/CHANGELOG.md

Package MR

big-bang/product/packages/mattermost!284 (merged)

For Issue

Closes big-bang/product/packages/mattermost#186 (closed)

Upgrade Notices

N/A