fix: Fetch parent block even when past reexecution deadline (#17872)

Attempts fetching the parent block when computing an attestation even if
past the reexecution deadline. This may fix flakes in tests where
reexecution is not needed, in particular inactivity slash.

Author: spalladino

yarn-project/validator-client/src/block_proposal_handler.ts

@@ -135,21 +135,18 @@ export class BlockProposalHandler {
       const currentTime = this.dateProvider.now();
       const timeoutDurationMs = deadline.getTime() - currentTime;
       const parentBlock =
-        timeoutDurationMs <= 0
+        (await this.blockSource.getBlock(blockNumber - 1)) ??
+        (timeoutDurationMs <= 0
           ? undefined
           : await retryUntil(
               async () => {
-                const block = await this.blockSource.getBlock(blockNumber - 1);
-                if (block) {
-                  return block;
-                }
                 await this.blockSource.syncImmediate();
                 return await this.blockSource.getBlock(blockNumber - 1);
               },
               'Force Archiver Sync',
               timeoutDurationMs / 1000,
               0.5,
-            );
+            ));
 
       if (parentBlock === undefined) {
         this.log.warn(`Parent block for ${blockNumber} not found, skipping processing`, proposalInfo);