Update Default Mattermost Values

Package Merge Request

Package Changes

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Default values changes

When Mattermost has a process performed that changes the value of DB_CONNECTION_STRING, the string stored in the database does not get updated. This MR adds usage of the MM_SQLSETTINGS_DATASOURCE env var to check this secret key by default and respect any changes that occur.

Checking env on default dev deployment:

Updated secret to simulate change in the value of DB_CONNECTION_STRING and bounced pod. Only changed timeout for the purposes of showing that it works:

Package MR

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For Issue

Closes #2308 (closed)

Upgrade Notices

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