test: update a few indentation related diagnostics
Previously, these were pointing to the right place, but were missing the
`^`. With the `annotate-snippets` upgrade, the `^` was added, but they
started pointing to the end of the previous line instead of the
beginning of the following line. In this case, we really want it to
point to the beginning of the following line since we're calling out
indentation issues.
As in a prior commit, we fix this by tweaking the offsets emitted by the
lint itself. Instead of an empty range at the beginning of the line, we
point to the first character in the line. This "forces" the renderer to
point to the beginning of the line instead of the end of the preceding
line.
The end effect here is that the rendering is fixed by adding `^` in the
proper location.
