bob-sepolia: add Jovian to EL genesis; drop redundant op-node override

genesis.json had no jovianTime, so op-geth/op-reth never activated Jovian
and op-node rejected Jovian-era L1-info txs ("unexpected length"). Added
jovianTime=1772548201 to the genesis config (EL source of truth for both
geth and reth). Removed OP_NODE_OVERRIDE_JOVIAN from the op-node env: the
local rollup.json already carries jovian_time, making the override redundant.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

op/bob/sepolia/genesis.json

@@ -25,6 +25,7 @@
       "graniteTime": 1725984001,
       "holoceneTime": 1732633200,
       "isthmusTime": 1744905600,
+      "jovianTime": 1772548201,
       "pragueTime": 1744905600,
       "terminalTotalDifficulty": 0,
       "terminalTotalDifficultyPassed": true,