[MM-53990] Support a global retention time of less than 1 day (#25196)

* adding new MessageRetentionHours config

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Co-authored-by: Mattermost Build <build@mattermost.com>

e2e-tests/playwright/support/server/default_config.ts

@@ -611,7 +611,9 @@ const defaultServerConfig: AdminConfig = {
         EnableFileDeletion: false,
         EnableBoardsDeletion: false,
         MessageRetentionDays: 365,
+        MessageRetentionHours: 0,
         FileRetentionDays: 365,
+        FileRetentionHours: 0,
         BoardsRetentionDays: 365,
         DeletionJobStartTime: '02:00',
         BatchSize: 3000,