[CodeCompletion] Disable multi trailing closure completion at newline
let value = SomeThing {
...
}
<HERE>
Since Parser parses code-completion token as a part of the expression,
completion failed to suggest 'value'. Also, the type of 'value' is
often '<<error type>>' because of the code completion token.
For now, disable additional trailing closure completion (suggesting
'label: { <#code#> }') on newline positions. Users still get the
compltion on the same line as the closing brace.
rdar://problem/66456159
(cherry picked from commit 5936ddb2171c07e35ab4d0f066274ff8fa48c9a0)