Add test coverage for server message processor management functions

[coderabbitai[bot]]

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The functions managing server message processors in packages/mcots/messageProcessors/index.ts lack test coverage. This is important for ensuring their reliability. Please add unit tests for these functions.\n\nPR URL: https://github.com/rustymotors/server/pull/2037\nComment URL: https://github.com/rustymotors/server/pull/2037#discussion_r1724152008