[test] Disable cursor_no_cancel test that crashes occassionaly in CI

Need to investigate this before reenabling.

Author: benlangmuir

test/SourceKit/CursorInfo/cursor_no_cancel.swift

@@ -44,3 +44,6 @@ func myFunc() {
 // RANGE: source.lang.swift.range.singleexpression
 // RANGE: source.lang.swift.range.singleexpression
 // RANGE: source.lang.swift.range.singleexpression
+
+// FIXME: this crashes very infrequently in CI
+// REQUIRES: disabled