extension/package.json: fix typo in debug/callstack/context

This patch fixes problem when user try debug not golang program, but see
"Go: Toggle Hide System Goroutines" command for threads in callstack view.

Change-Id: I3eb622fa6f6b913d107c50145d2061a0a977e7a5
GitHub-Last-Rev: 5d2a74e
GitHub-Pull-Request: #3778
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/679795
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Madeline Kalil <mkalil@google.com>
Reviewed-by: Hongxiang Jiang <hxjiang@golang.org>

Author: DrSergei

extension/package.json

@@ -3492,7 +3492,7 @@
       "debug/callstack/context": [
         {
           "command": "go.debug.toggleHideSystemGoroutines",
-          "when": "debugType == 'go' && callStackItemType == 'stackFrame' || (callStackItemType == 'thread' && callStackItemStopped)"
+          "when": "debugType == 'go' && (callStackItemType == 'stackFrame' || (callStackItemType == 'thread' && callStackItemStopped))"
         }
       ],
       "editor/context": [