Change the default value of `io.etcd.jetcd.launcher.Etcd.Builder#shouldMountDataDirectory` to `false`

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- See https://github.com/etcd-io/jetcd/issues/1310#issuecomment-2275551008 .

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- Change the default value of `io.etcd.jetcd.launcher.Etcd.Builder#shouldMountDataDirectory` to `false`. After all, it's tedious to always require users to manually change configurations related to user groups. See https://github.com/etcd-io/jetcd/blob/jetcd-0.8.6/jetcd-launcher/src/main/java/io/etcd/jetcd/launcher/Etcd.java .

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Open jetcd-launcher/src/main/java/io/etcd/jetcd/launcher/Etcd.java and inspect the Builder#shouldMountDataDirectory entry. Change its default value to false, then verify that the builder now uses false when callers do not provide an override.

Written by the indexing model from the issue text.