Flow: Remove unussed '$FlowIssue' (#2026)

Author: IvanGoncharov

.flowconfig

@@ -32,7 +32,6 @@ unnecessary-invariant=off
 include_warnings=true
 module.use_strict=true
 suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe\\($\\|[^(]\\|(\\(<VERSION>\\)?)\\)
-suppress_comment=\\(.\\|\n\\)*\\$FlowIssue\\((\\(<VERSION>\\)?)\\)?:? #[0-9]+
 suppress_comment=\\(.\\|\n\\)*\\$DisableFlowOnNegativeTest
 
 [version]