MB-67049: Split RangeScanCreateAndContinueTest into 4 groups

4 fixtures so CV runs this test in smaller groups.

Change-Id: I109d558c835df10cd82fd6970f71f29d21cd5ba6
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/229801
Tested-by: Jim Walker <[email protected]>
Reviewed-by: Trond Norbye <[email protected]>

Author: jimwwalker