Regression with 0.5.0.0: Fix indentation after a list comprehension with infix operator

Fourmolu unexpectedly changes
```hs
x =
  [1 | _ <- _]
    <> [2]
```
to
```hs
x =
  [1 | _ <- _]
  <> [2]
```
This only seems to happen with list comprehensions. This occurred when merging Ormolu 0.4.0.0; Ormolu has this correct

https://github.com/fourmolu/fourmolu/pull/138#discussion_r758708927