[Bug]: Signatures - Pending Signature is displayed in all accounts Activity

**Describe the bug**

Whenever we are triggering a Signature and we have it pending in the Activity tab, no matter which account I select we are going to see the pending signature.

**Expected behavior**

Only display it in the Account that has triggered the Signature?
I think maybe the logic would need to change significantly to support this though, so not 100% sure

**Screenshots/Recordings**

https://github.com/MetaMask/metamask-extension/assets/54408225/91cef618-432c-4786-83d3-44c0f65e4a5b

**Steps to reproduce**

1. Trigger a Signature from a dapp
2. Go to MM full view
3. Change Accounts
4. Click on the Activity tab
5. See Pending signature is there
6. Change Accounts
7. See Pending signature is also there

**Version**

production (old issue)

**Build type**

None

**Browser**

Chrome

**Operating system**

Linux

Start with the Activity tab and the account-selection flow described in the reproduction steps. Trace how a pending Signature is associated with an account, then verify the behavior by triggering a Signature from a dapp and switching accounts in full view. Done means the pending Signature appears only for the account that triggered it.

Written by the indexing model from the issue text.