[explorer] remove cache param (MystenLabs#11735)

## Description 

remove unneeded param from validator map query

## Test Plan 

locally

---
If your changes are not user-facing and not a breaking change, you can
skip the following section. Otherwise, please indicate what changed, and
then add to the Release Notes section as highlighted during the release
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### Type of Change (Check all that apply)

- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes

apps/explorer/src/components/validator-map/index.tsx

@@ -89,8 +89,6 @@ export default function ValidatorMap({ minHeight }: Props) {
         setIsLoading(true);
         appsBe(`validator-map`, {
             network: network.toLowerCase(),
-            // TODO: remove when caching solution is improved
-            skipCache: true,
         })
             .then((res) => {
                 const data = res as ValidatorMapData[];