Revert mainnet USDC token support change (#2410)

## Summary
- Revert the USDC mainnet support update that was already merged in
commit 94dae94.
- Restore legacy behavior for token metadata and mainnet token indexing
entries.
- No functional changes beyond the rollback are included.

## Commit(s)
- 41e7b70 Revert "feat: add new mainnet USDC and label legacy as
USDC.e"

Author: tarrencev

packages/keychain/src/utils/token-metadata.ts

@@ -22,12 +22,6 @@ const CACHED_TOKEN_METADATA: Record<string, TokenMetadata> = {
     symbol: "USDC",
     decimals: 6,
   },
-  // USDC.e on mainnet (legacy)
-  "0x053c91253bc9682c04929ca02ed00b3e423f6710d2ee7e0d5ebb06f3ecf368a8": {
-    name: "USD Coin",
-    symbol: "USDC.e",
-    decimals: 6,
-  },
   // USDC on sepolia
   [USDC_ADDRESSES[constants.StarknetChainId.SN_SEPOLIA].toLowerCase()]: {
     name: "USD Coin",

packages/torii-config/public-tokens/mainnet.toml

@@ -9,10 +9,8 @@ contracts = [
   "erc20:0x049d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7",
   # STRK
   "erc20:0x04718f5a0fc34cc1af16a1cdee98ffb20c31f5cd61d6ab07201858f4287c938d",
-  # USDC.e
-  "erc20:0x053c91253bc9682c04929ca02ed00b3e423f6710d2ee7e0d5ebb06f3ecf368a8",
   # USDC
-  "erc20:0x033068f6539f8e6e6b131e6b2b814e6c34a5224bc66947c47dab9dfee93b35fb",
+  "erc20:0x053c91253bc9682c04929ca02ed00b3e423f6710d2ee7e0d5ebb06f3ecf368a8",
   # USDT
   "erc20:0x068f5c6a61780768455de69077e07e89787839bf8166decfbf92b645209c0fb8",
   # DAI