test: add epoch_boundary sanity runner case for nightly spec tests

Upstream consensus-specs ChainSafe#5127 adds epoch_boundary sanity tests for
Gloas (and post-Gloas `heze`). The case format is identical to blocks
(pre / post / blocks_N / meta.blocks_count), so route it through the
existing sanityBlocks runner.

Surfaced by pnpm test:spec:minimal against nightly artifacts downloaded
via the new nightly workflow in ChainSafe#9221.

🤖 Generated with AI assistance

Author: lodekeeper

packages/beacon-node/test/spec/presets/sanity.test.ts

@@ -23,6 +23,7 @@ const sanity: TestRunnerFn<any, BeaconStateAllForks> = (fork, testName, testSuit
     case "slots":
       return sanitySlots(fork, testName, testSuite);
     case "blocks":
+    case "epoch_boundary":
       return sanityBlocks(fork, testName, testSuite);
     default:
       throw Error(`Unknown sanity test ${testName}`);