Vetos: percentages over 100%

As a scientist on MARI I am confused about the DAE having vetoed 37598400% of my last run due to external veto 2.


### Acceptance criteria:
- vetos panel does not display non-sensical percentages of vetos

### Notes

I believe this is a server-side issue as caget also reports these nonsense percentages:
```
caget -S IN:MARI:DAE:VETOSTATUS
IN:MARI:DAE:VETOSTATUS FIFO Veto() is ENABLED (vetoed 0) frames\nSMP (chopper) Veto() is ENABLED (vetoed 150821) frames\nFermi Chopper0 Veto() is ENABLED (vetoed 15074) frames\nTS2 Pulse Veto() is DISABLED (counted 90438) frames\nISIS 50 Hz Veto() is DISABLED (counted 25) frames\nExternal Veto 0(Disks 1 & 2) is ENABLED (vetoed 5329) frames\nExternal Veto 1(T0) is ENABLED (vetoed 4315) frames\nExternal Veto 2(Moderator) is ENABLED (vetoed 375984) frames\nExternal Veto 3() is DISABLED (counted 452345) frames\n\nFIFO Veto() vetoed 0% (last 2 seconds), 0% (since run start)\nSMP (chopper) Veto() vetoed 0% (last 2 seconds), 15082100% (since run start)\nFermi Chopper0 Veto() vetoed 0% (last 2 seconds), 1507400% (since run start)\nExternal Veto 0(Disks 1 & 2) vetoed 0% (last 2 seconds), 532900% (since run start)\nExternal Veto 1(T0) vetoed 0% (last 2 seconds), 431500% (since run start)\nExternal Veto 2(Moderator) vetoed 0% (last 2 seconds), 37598400% (since run start)\n\nLast Updated: 11:27:13
```