Bigger thread dependent initial window.
Increase the initial delta of the aspiration window by "thread id mod 8".
Passed SMP STC:
LLR: 2.96 (-2.94,2.94) <0.00,2.00>
Total: 106176 W: 27470 L: 27069 D: 51637
Ptnml(0-2): 121, 12032, 28386, 12423, 126
https://tests.stockfishchess.org/tests/view/68a178fab6fb3300203bbaec
Passed SMP LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 133076 W: 34272 L: 33772 D: 65032
Ptnml(0-2): 38, 13709, 38537, 14223, 31
https://tests.stockfishchess.org/tests/view/68a1b5d2b6fb3300203bbb71
closes https://github.com/official-stockfish/Stockfish/pull/6239
No functional change