[gopls-release-branch.0.6] internal/lsp: remove module diagnostics from code actions

With -mod=readonly, all go.mod diagnostics are covered by go get quick
fixes on import statements, so we don't need to run `go mod tidy` on
save for Go files. The real issue with this bug is the call to
WorkspacePackages, which type checks every package in the workspace.

Fixes golang/go#45092

Change-Id: Ibb82a3e58ec345ebdb67c0cbef5e029dce2d5a30
Reviewed-on: https://go-review.googlesource.com/c/tools/+/303149
Trust: Rebecca Stambler <[email protected]>
Run-TryBot: Rebecca Stambler <[email protected]>
gopls-CI: kokoro <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Heschi Kreinick <[email protected]>
(cherry picked from commit 2c4a886)
Reviewed-on: https://go-review.googlesource.com/c/tools/+/303150

Author: stamblerre

internal/lsp/code_action.go

@@ -138,19 +138,6 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 			return nil, err
 		}
 		fileDiags := append(pkgDiagnostics[uri], analysisDiags[uri]...)
-		modURI := snapshot.GoModForFile(fh.URI())
-		if modURI != "" {
-			modFH, err := snapshot.GetVersionedFile(ctx, modURI)
-			if err != nil {
-				return nil, err
-			}
-			modDiags, err := mod.DiagnosticsForMod(ctx, snapshot, modFH)
-			if err != nil && !source.IsNonFatalGoModError(err) {
-				// Not a fatal error.
-				event.Error(ctx, "module suggested fixes failed", err, tag.Directory.Of(snapshot.View().Folder()))
-			}
-			fileDiags = append(fileDiags, modDiags...)
-		}
 
 		// Split diagnostics into fixes, which must match incoming diagnostics,
 		// and non-fixes, which must match the requested range. Build actions