Remove RPC messages pertaining to the LLM token (#36252)

This PR removes the RPC messages pertaining to the LLM token.

We now retrieve the LLM token from Cloud.

Release Notes:

- N/A

crates/proto/src/proto.rs

@@ -119,8 +119,6 @@ messages!(
     (GetTypeDefinitionResponse, Background),
     (GetImplementation, Background),
     (GetImplementationResponse, Background),
-    (GetLlmToken, Background),
-    (GetLlmTokenResponse, Background),
     (OpenUnstagedDiff, Foreground),
     (OpenUnstagedDiffResponse, Foreground),
     (OpenUncommittedDiff, Foreground),
@@ -196,7 +194,6 @@ messages!(
     (PrepareRenameResponse, Background),
     (ProjectEntryResponse, Foreground),
     (RefreshInlayHints, Foreground),
-    (RefreshLlmToken, Background),
     (RegisterBufferWithLanguageServers, Background),
     (RejoinChannelBuffers, Foreground),
     (RejoinChannelBuffersResponse, Foreground),
@@ -354,7 +351,6 @@ request_messages!(
     (GetDocumentHighlights, GetDocumentHighlightsResponse),
     (GetDocumentSymbols, GetDocumentSymbolsResponse),
     (GetHover, GetHoverResponse),
-    (GetLlmToken, GetLlmTokenResponse),
     (GetNotifications, GetNotificationsResponse),
     (GetPrivateUserInfo, GetPrivateUserInfoResponse),
     (GetProjectSymbols, GetProjectSymbolsResponse),