Disable vtsls by default (#12611)

This PR adds default settings to disable `vtsls` by default so that
there aren't multiple TypeScript language servers running.

I also renamed the language server from `vtsls-language-server` to just
`vtsls`, since the `-language-server` suffix was redundant.

Release Notes:

- N/A

assets/settings/default.json

@@ -700,6 +700,7 @@
       }
     },
     "JavaScript": {
+      "language_servers": ["typescript-language-server", "!vtsls", ".."],
       "prettier": {
         "allowed": true
       }
@@ -748,6 +749,7 @@
       }
     },
     "TSX": {
+      "language_servers": ["typescript-language-server", "!vtsls", ".."],
       "prettier": {
         "allowed": true
       }
@@ -758,6 +760,7 @@
       }
     },
     "TypeScript": {
+      "language_servers": ["typescript-language-server", "!vtsls", ".."],
       "prettier": {
         "allowed": true
       }