core/config: Stop doing copy on write (#1724)
core/config: Stop doing copy on write (#1724)

When persisting the config, we use a temporary file to avoid losing
data if writing the config file fails.
When we introduced this mechanism, we decided to use copy on write but
this seems to lead to errors on macOS and is not really necessery
after all.
cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop