[Status Network Contracts] Slashing over estimates penalty in some scenarios

[0x-r4bbit]

Context: https://github.com/Cyfrin/audit-2025-12-statusl2/issues/7

TLDR;

• While slash percentage is 50%, in some conditions, slashing can result in burning more than an account's 50%
• This happens because we round the slash amount per reward distributor up, if the 50% to be slashed is < 1e18

Fix is to check for minimum slash amount on the total 50% once