Disable a flaky lldb-vscode test on aarch64

Summary:
These tests isflaky only on this arch for some reason. It's testing important features and is not flaky on x86_64, so I'll investigate this arm issue separatedly.

A flaky run:
http://lab.llvm.org:8011/builders/lldb-aarch64-ubuntu/builds/5540/steps/test/logs/stdio

Diff that created those tests:
https://reviews.llvm.org/D81978