Speeds up ASG syncing and Querying

[geofffranks]

• Read the Contributing document.

Summary

• Normalizes DB data with join tables associating security_groups and spaces
• Adds a migration to prepopulate associations prior to the next sync
• When syncing, asg-syncer only updates security groups in the database that have changed compared to the existing data
• Database updates are done in bulk to speed up transaction time
• Significantly speeds up the database query for retrieving security groups by space guid using the normalized tables for filtering
• small enhancements/fixes to cf multispace pusher (used for scaling out envs for testing)

Backward Compatibility

Breaking Change? No

[geofffranks]

Perf Testing Environment:
350 cells, 13k apps, 15k spaces, 40k security groups, 47k security group-space associations, 50 global asgs, 100 asgs bound to 75 spaces each, avg security group size 200 rules,

policy-server-asg-syncer results:
SecurityGroupsTotalSyncTime: ~6s for a single asg changing, 16s for all asgs changing.

vxlan-policy-server sync results (when cells were limited to having 200k iptables rules):
asgTotalPollTime: 25-50s

Overall results will depend on cloud controller + database load, as this deployment was isolated for testing just ASG performance.

When no changes are occuring, sync times are ~100ms for each process.