mattermod: propagate error from (s *Server).checkCLA upwards

Description

This method ignores a lot of errors like `_ = s.createRepoStatus(ctx, pr, status)` and in many cases, sometimes logs the error and sometimes completely ignores handling the error.

We should fix all of these and propagate the error upwards.

QA Test Steps

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Mana

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Assignee

Ibrahim Acikgoz

QA Assignee

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Reporter

Agniva De Sarker

Epic Link

Fix versions

Mattermost Team

Platform

Sprint

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Labels

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QA Testing Areas

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GitHub Issue

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