MB-12156 Don't delete buckets when changing datapath.

Change-Id: I8d37f92f2d06cca9648f20b40eeae2642d0a91ac
Reviewed-on: http://review.couchbase.org/41332
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-12156 Don't trap exits while change disk paths.

It's not needed and prevents us from a situation where process gets
stuck and wakes up much later (potentially after node became part of a
cluster) and thus invalidates the check that node is not provisioned.

Change-Id: Ie0f9ced83150ddca71781704c05a350dd4b6a271
Reviewed-on: http://review.couchbase.org/41333
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>