Adjust restart world logging level to match start major/nursery logging. (mono/mono...

Adjust restart world logging level to match start major/nursery logging. (mono/mono#17520)

With this change we will get the following logging on level 1:

2019-10-22 15:46:59 Start nursery collection 38898 00000205A0000000-00000205A1000000, size: 16777216
2019-10-22 15:46:59 restarted (pause time: 2728 usec, max: 689233 usec)

showing the pause time and when runtime was restared, before this fix
we will only see the start log message on level 1.

Commit migrated from https://github.com/mono/mono/commit/fe7654f745c9b8ba030c9c4c1671904c6d9bda53