Remove builtin snippets (in favour of server-based completion)

[radeksimko]

Background

Builtin snippets are generally context-less, unlike completion from the language server. Therefore, every single completion popup contains the same options, whether or not they're relevant.

Furthermore, in most cases this is duplicated in combination with completion options from the server.

Proposal

• [x] https://github.com/hashicorp/terraform-ls/issues/496
  • [ ] Bump language server to ensure ^ logic is available in the extension
• [ ] Remove all existing snippets https://github.com/hashicorp/vscode-terraform/blob/1b4b0ed68ec39bc131246aef0de1f20265ad3a0a/package.json#L265-L270