[Trivial] Fix indentation in test_dash.cpp

[PastaPastaPasta]

based on #3310

[codablock]

needs rebase

[UdjinM6]

utACK

[codablock]

nACK

This will cause merge conflicts in future backports and is not worth the trouble. The indention is/was wrong in Bitcoin as well and later backports will fix it.

[PastaPastaPasta]

Due to the fact that we renamed it to test_dash any changes to test_bitcoin automatically are conflicts(this is at least what I experienced in my backporting). When I backported changes to test_bitcoin I had to do it manually.

[UdjinM6]

I tend to agree with @PastaPastaPasta on that one tbh... Indentation here won't be fixed until 0.19, plus this file should not be touched that often in following backports really. IMO it's ok-ish to fix it now.

[codablock]

@PastaPastaPasta -Xrename-threshold=20% as git argument helps in such cases when cherry picking commits that involve files that we have internally renamed. There is also the rename from test_bitcoin.cpp -> setup_common.cpp which will happen in one of the future versions, and this one will be a candidate for many conflicts.