MB-12793: Initialize bucketCreation flags to false

bucketCreation flags should be initialized to false.
This flag is set to true for every vbucket during creation,
and once VBStatePersistTask completes, the flag is set back
to false.

Change-Id: Ib0837b6f584beb3aeeb924499b0642fbb540f1f0
Reviewed-on: http://review.couchbase.org/44208
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: abhinav dangeti <abhinav@couchbase.com>