Dashboard: Remove OP Sponsored badge in Chain selector (#7948)

<!--

## title your PR with this format: "[SDK/Dashboard/Portal] Feature/Fix: Concise title for the changes"

If you did not copy the branch name from Linear, paste the issue tag here (format is TEAM-0000):

## Notes for the reviewer

Anything important to call out? Be sure to also clarify these in your comments.

## How to test

Unit tests, playground, etc.

-->

<!-- start pr-codex -->

---

## PR-Codex overview
This PR removes the handling of sponsored chains from the `CustomChainRenderer` component, including the related constant and UI elements that indicate whether a chain is sponsored.

### Detailed summary
- Deleted the import of `OPSponsoredChains` from `@/constants/chains`.
- Removed the `isSponsored` variable that checks if a chain is sponsored.
- Eliminated the UI block that displayed "Sponsored" for sponsored chains.

> ✨ Ask PR-Codex anything about this PR by commenting with `/codex {your question}`

<!-- end pr-codex -->

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- Refactor
  - Removed the Sponsored badge from the chain list, simplifying the chain renderer.
  - Deprecated chains still display a Deprecated badge and remain non-interactive.
  - Clicking non-deprecated chains continues to switch networks; the Configure Network button is unchanged.

- Chores
  - Removed obsolete sponsor-related configuration and references.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: MananTank

apps/dashboard/src/@/components/misc/CustomChainRenderer.tsx

@@ -3,7 +3,6 @@ import type { ThirdwebClient } from "thirdweb";
 import type { UseNetworkSwitcherModalOptions } from "thirdweb/react";
 import { Button } from "@/components/ui/button";
 import { Spinner } from "@/components/ui/Spinner";
-import { OPSponsoredChains } from "@/constants/chains";
 import { useAllChainsData } from "@/hooks/chains/allChains";
 import { ChainIconClient } from "@/icons/ChainIcon";
 import { cn } from "@/lib/utils";
@@ -32,7 +31,6 @@ export const CustomChainRenderer = ({
   const { idToChain } = useAllChainsData();
   const storedChain = idToChain.get(chain.id);
   const isDeprecated = storedChain?.status === "deprecated";
-  const isSponsored = OPSponsoredChains.includes(chain.id);
 
   return (
     <div className="flex min-h-[48px] w-full cursor-pointer justify-start rounded-lg px-2 py-1 hover:bg-accent">
@@ -70,16 +68,6 @@ export const CustomChainRenderer = ({
                   Deprecated
                 </div>
               )}
-              {isSponsored && (
-                <div
-                  className="flex shrink-0 cursor-not-allowed items-center overflow-hidden rounded-xl px-2 py-1 font-medium text-xs"
-                  style={{
-                    background: "linear-gradient(to right, #701953, #5454B2)",
-                  }}
-                >
-                  Sponsored
-                </div>
-              )}
             </div>
             {switching && (
               <div className="flex items-center gap-1 font-medium text-link-foreground text-xs">