Cannot edit gas price when signing multiple transactions

**Describe the bug**
If a dapp initiates multiple transactions, the first transaction's gas can be edited, however, the 2nd on are uneditable.

**To Reproduce**

1. Go to tokentrove.com
2. select an item, then click "buy multiple"
3. enter 2 or more
4. confirm the first transaction
5. on the 2nd transaction, try to edit the gas (you will see it revert to the originally suggested gas price)

**Expected behavior**
Allow users to edit gas on every transaction.

**Additional context**
reddit post: https://www.reddit.com/r/Metamask/comments/e6238q/gas_price_does_not_stay_set_when_signing_multiple/

Edit by danjm, July 25, 2023:

I am changing this from a bug to an enhancement. As per Thomas' comments below, this was actually a user looking for functionality we never supported: the ability to edit gas once for multiple open transactions.

Start by reproducing the flow at tokentrove.com: initiate multiple transactions, confirm the first, and edit gas on the second. Trace the transaction confirmation and gas-editing entry points in the extension UI. Done means a user can edit gas for every transaction in a multi-transaction flow and the chosen value does not revert.

Written by the indexing model from the issue text.