fix: logout clear storage missing promise await

[peterpeterparker]

Description

The logout function does not await for the storage to be cleared before reloading the window. This can lead to an edge case race condition where the storage would partially cleared after logout while the window is reloaded.

Fixes # (issue)

NNS-dapp PR #1247

How Has This Been Tested?

Jest test in nns-dapp that failed:

it("agent-js should clear indexeddb auth info on logout", async () => {
      const idbStorage = new IdbStorage();
      await idbStorage.set("delegation", "value");

      const value = await idbStorage.get("delegation");
      expect(value).not.toBeNull();

      await logout({});

      const valueCleared = await idbStorage.get("delegation");
      expect(valueCleared).toBeNull(); // <--- value was still set
    });

Checklist:

• My changes follow the guidelines in CONTRIBUTING.md.
• The title of this PR complies with Conventional Commits.