SERVER-13391 Rename slowNightly -> noPassthroughWithMongod and slowWeekly -> noPassthrough

This better represents their purpose and the difference between them.

(cherry picked from commit d0a1e84ab2fa1b6aa699721b5cb9a4f8d0bf3692)
SERVER-13391 Move slowest tests from noPassthrough* (formerly slow{Weekly,Nightly}) to slow*

slow1 and slow2 are new suites to hold very slow tests. The idea is that we
can create slow3, slow4, etc to keep the time to run the longest suite down.

(cherry picked from commit 43d933a286bff0e98845368c84c10248388bc4a5)