Improve performance of StreamActiveComputations query.

[SanjayVas]

• Reorder index columns to actually be useful for query.
• Apply clauses to Measurements table before other joins.

[wfa-reviewable]

This change is 

[SanjayVas]

Sample queries from halo-cmm-dev:

• original-query.sql.txt
• updated-query.sql.txt

The updated query appears to halve the CPU time.