Set a default value for bolt_timeout within scorch

etcd-io/bbolt advertises that it acquires a file lock on the data file so multiple processes cannot open the same database at the same time.

But as highlighted in CBSE-11519, the goroutine traces show that there's a situation where the janitor is stuck trying to acquire bolt's file lock indefinitely.

This was also flagged by a community user here - https://github.com/blevesearch/bleve/issues/1491

We've gone ahead and introduced a way to set a timeout provided by bbolt to not wait indefinitely with this change .. https://github.com/blevesearch/bleve/pull/1553

This change is available since couchbase-server 7.0 (I forget the exact build). This timeout setting can be introduced by making a change to the index definition.

Perhaps it might prove helpful to set a default value for this setting.