[lldb] Remove trailing newlines from AppendErrorWithFormat calls (#192965)
This call adds a newline if there isn't one. Changing these will
eventually let us always add a newline, which is in line with the other
methods on CommandReturnObject.
This is a small part of calls found with:
* VSCode search for
`(\.AppendErrorWithFormat\(([\s\r\n]+)?"(?:(?:\\.|[^"\\])*))\\n"` and
replace with `$1"`.
* Asserting that the last character of the format string is not a
newline.
* Manual inspection.