chore: bump validator resource requests (#4288)

### Description

See thread
https://discord.com/channels/935678348330434570/935679524534911007/1271367720797077548
for context.

TLDR:
- upon starting up, validators tend to use more CPU and memory, and this
scales a bit with # of messages previously dispatched on that chain
- nothing concerning, but we were exceeding the 75% usage / requests
threshold on some of our alerts, so bumping to give some room

### Drive-by changes

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### Related issues

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- Fixes #[issue number here]
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### Backward compatibility

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### Testing

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typescript/infra/config/environments/mainnet3/agent.ts

@@ -296,8 +296,8 @@ const relayerResources = {
 
 const validatorResources = {
   requests: {
-    cpu: '250m',
-    memory: '256Mi',
+    cpu: '500m',
+    memory: '1Gi',
   },
 };