Klaus Post 6a8298b137
Reduce Mutex test runs (#9345)
Some tests take a long time on CI:

* `--- PASS: TestRWMutex (226.49s)`
* ` --- PASS: TestRWMutex (7.13s)`

Reduce the number of runs.

Before/after locally:

```
--- PASS: TestRWMutex (20.95s)
--- PASS: TestRWMutex (7.13s)

--- PASS: TestMutex (3.01s)
--- PASS: TestMutex (1.65s)
```
2020-04-14 18:39:03 -07:00
..
2020-04-14 18:39:03 -07:00
2019-11-19 17:42:27 -08:00