Uninstalls duplicate MCP

[sergeibbb]

Description

Fixes #4626

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[sergeibbb]

@eamodio I have one doubt here.

I suppose, the result of the fix should give us the following:

• User comes to us and says "I have duplication of MCP"
• We say: "Try one of the following" (both work):

1. Reload your IDE window
2. Call GitLens: Reinstall GitKraken MCP in the command palette.

However, now we might have problem with the option #2.

That's because, I call deduping after the successful config call, here:

But it's never called twice until the version of the GK CLI is updated:

Therefore, the question is the following:

1. Is it OK that the second recipe won't always work (only once per launch)
2. Or is it better to move deduping command to another place? e.g. from onRegistrationCompleted to getMcpConfigurationFromCLI ?

cc @axosoft-ramint