[bugfix] Fix duplicating fields on profile edit

[tsmethurst]

Description

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If this is a documentation change, please briefly describe what you've changed and why.

This PR fixes fields being duplicated when profile was updated but fields were left untouched. Issue was that we weren't resetting the accounts field's slice. Now we are! Added tests too, booya

Checklist

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• I/we have read the GoToSocial contribution guidelines.
• I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• I/we have performed a self-review of added code.
• I/we have written code that is legible and maintainable by others.
• I/we have commented the added code, particularly in hard-to-understand areas.
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• I/we have added tests that cover new code.
• I/we have run tests and they pass locally with the changes.
• I/we have run go fmt ./... and golangci-lint run.

[tsmethurst]

This is the fix.

[tsmethurst]

This tests the fix

[tsmethurst]

npm registry is struggling, which is causing the web build portion of the cicd to fail, will run this again in a couple hours