Reland "[scudo] Apply filling when realloc shrinks and re-grows a block in-place" (#95838)

Reland of #93212, which had been reverted in
commit bddd8eae17df6511aee789744ccdc158de817081.

GitOrigin-RevId: 7fc975aa26f2e0ce6c80629209115ea58b245da5
2 files changed