Investigate ns_server/collection differences in compaction tests

Cloned from MB-44539 so that analysis for beam.smp isn't lost in my myriad of updates regarding the memcached analysis.

The following text is the orginal summary from Korrigan and i've highlighted the beam.smp questions.

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