Investigate bucket/collection differences in compaction tests

For our compaction time tests there are some differences seen when comparing default collection (bucket) to 1 scope 1 collection, 1 scope 1000 collections, and 1000 scopes 1000 collections.

Showfast page for all the tests: 

http://showfast.sc.couchbase.com/#/timeline/Linux/kv/compact/all

Note: default collection (bucket) test uses python sdk2 and the rest of the tests use python sdk3. There is a higher in the number of connection made per client in sdk3.

default vs. 1 scope 1 collection:

graph comparison - http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=athena_700-4502_compact_e699&label=default&snapshot=athena_700-4502_compact_cd05&label=1s1c

1 - mem_used and ep_meta_data_memory in 1 collection case is higher than for default and trends lower, whereas default trends higher throughout the test

2 - vb_active_resident_items_ratio is 25% higher in 1 collection case

3 - vb_replica_resident_items_ratio starts higher and trends lower in 1 collection case, whereas default trends higher

4 - avg_disk_commit_time, avg_disk_update_time, vb_avg_total_queue_age are higher for all percentiles in 1 collection case

5 - couch_docs_actual_disk_size and couch_docs_fragmentation starts 25% higher in 1 collection case

6 - memcached_rss 15% higher in 1 collection case

7 - Cached (memory in pagecache) is 5% lower in 1 collection case

default vs 1 scope 1000 collections:

graph comparison - http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=athena_700-4502_compact_e699&label=default&snapshot=athena_700-4502_compact_a7b7&label=1s1000c

1 - vb_active_resident_items_ratio is 100% higher in 1 scope 1000 collection case

2 - vb_replica_resident_items_ratio is less than 1% (near 0%)  in 1 scope 1000 collection case, whereas default is around 5%

3 - couch_docs_actual_disk_size is 40% higher in 1 scope 1000 collection case

4 - couch_docs_fragmentation is 50% higher in 1 scope 1000 collection case

5 - beam.smp_rss is 250% higher in 1 scope 1000 collection case

6 - beam.smp_cpu is 600% higher in 1 scope 1000 collection case

7 - memcached_cpu is 25% higher in 1 scope 1000 collection case

default vs 1000 scopes 1000 collections:

graph comparison - http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=athena_700-4502_compact_e699&label=default&snapshot=athena_700-4502_compact_0315&label=1000s1000c

1 scope 1000 collections vs. 1000 scopes 1000 collections:

graph comparison - http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=athena_700-4502_compact_a7b7&label=1s1000c&snapshot=athena_700-4502_compact_0315&label=1000s1000c

1 - avg_disk_update_time is higher for all percentiles in 1000 scope 1000 collection case.

2 - beam.smp_rss is 10% higher in 1000 scope 1000 collection case

3 - beam.smp_cpu is 70% higher in 1000 scope 1000 collection case