MM-31064: Simplify indentation (#16565)

* MM-31064: Simplify indentation

Reduce indentation where possible.

```release-note
NONE
```

Command ran to verify:
golangci-lint run --disable-all --enable golint --max-issues-per-linter=10000 --max-same-issues=100000 ./... | grep "block ends with a return state"

https://mattermost.atlassian.net/browse/MM-31064

* incorporate review comments

* enable golint for outdent rule

* fix remaining issues

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/slashcommands/command_msg.go

@@ -85,9 +85,8 @@ func (*msgProvider) DoCommand(a *app.App, args *model.CommandArgs, message strin
 			if directChannel, err = a.GetOrCreateDirectChannel(args.UserId, userProfile.Id); err != nil {
 				mlog.Error(err.Error())
 				return &model.CommandResponse{Text: args.T("api.command_msg.dm_fail.app_error"), ResponseType: model.COMMAND_RESPONSE_TYPE_EPHEMERAL}
-			} else {
-				targetChannelId = directChannel.Id
 			}
+			targetChannelId = directChannel.Id
 		} else {
 			mlog.Error(channelErr.Error())
 			return &model.CommandResponse{Text: args.T("api.command_msg.dm_fail.app_error"), ResponseType: model.COMMAND_RESPONSE_TYPE_EPHEMERAL}