[lldb] Use AppendMessageWithFormatv instead of AppendMessageWithFormat (#185634)

Part 4. This converts all the remaining simple uses (the ones that ended
with a newline).

What remains in tree are the outliers that expect multiple ending
newlines, or are building a message in pieces.

GitOrigin-RevId: 85446d41458319709333355745b8c8574c52d05f