fix: update OPTIMISM_TESTNET to OPTIMISM_SEPOLIA (#4015)

## Explanation

This PR replaces the reference to OP goerli to OP sepolia. It also
renames the variable `OPTIMISM_TESTNET` to `OPTIMISM_SEPOLIA`.

Only made this change on the transaction controller.

Renaming the variable and switching to Sepolia is a breaking change,
please use Sepolia and `OPTIMISM_SEPOLIA` instead of `OPTIMISM_TESTNET`.

## References

* Fixes MetaMask/mobile-planning#1569
* Related to
[#67890](MetaMask/metamask-mobile#8784)

## Changelog

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### `@metamask/transaction-controller`

**Removed**

- **BREAKING**: Renamed `OPTIMISM_TESTNET` to `OPTIMISM_SEPOLIA` and
updated the chainId accordingly.
- **BREAKING**: Updated the etherscan subdomain that was for
OPTIMISM_TESTNET from goerli to sepolia.


## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've highlighted breaking changes using the "BREAKING" category
above as appropriate

packages/transaction-controller/src/constants.ts

@@ -4,7 +4,7 @@ export const CHAIN_IDS = {
   BSC: '0x38',
   BSC_TESTNET: '0x61',
   OPTIMISM: '0xa',
-  OPTIMISM_TESTNET: '0x1a4',
+  OPTIMISM_SEPOLIA: '0xaa37dc',
   POLYGON: '0x89',
   POLYGON_TESTNET: '0x13881',
   AVALANCHE: '0xa86a',
@@ -64,10 +64,10 @@ export const ETHERSCAN_SUPPORTED_NETWORKS = {
     subdomain: `${DEFAULT_ETHERSCAN_SUBDOMAIN_PREFIX}-optimistic`,
     networkId: parseInt(CHAIN_IDS.OPTIMISM, 16).toString(),
   },
-  [CHAIN_IDS.OPTIMISM_TESTNET]: {
+  [CHAIN_IDS.OPTIMISM_SEPOLIA]: {
     domain: DEFAULT_ETHERSCAN_DOMAIN,
-    subdomain: `${DEFAULT_ETHERSCAN_SUBDOMAIN_PREFIX}-goerli-optimistic`,
-    networkId: parseInt(CHAIN_IDS.OPTIMISM_TESTNET, 16).toString(),
+    subdomain: `${DEFAULT_ETHERSCAN_SUBDOMAIN_PREFIX}-sepolia-optimistic`,
+    networkId: parseInt(CHAIN_IDS.OPTIMISM_SEPOLIA, 16).toString(),
   },
   [CHAIN_IDS.POLYGON]: {
     domain: 'polygonscan.com',