hil: increase settings response buffer

[szczys]

A new setting was added to the CI project which causes use to run out of space in the settings response buffer (used to report out-of-sunc settings). The result is that several settings test are failing on a no more core error:

<err> golioth_settings: Failed to send a response to server: -12

This commit doubles that buffer to avoid the error.

[github-actions[bot]]

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