fix: correct vim.lsp.client_is_stopped deprecation

[perrin4869]

this fix appears to have been mistakenly applied in reverse
I am getting the following warning, pointing to this file:

- ⚠️ WARNING vim.lsp.client_is_stopped() is deprecated. Feature will be removed in Nvim 0.14
  - ADVICE:
    - use vim.lsp.get_client_by_id() instead.

this change fixes the warning

[linrongbin16]

thank you!