Extremely large expense amount breaks stats display

[nus-pe-bot]

Expense entered: 999999999999999999999999999999999999999999999999999999

Worth noting that the heatmap and breakdown appear fine (although naturally the proportions of stuff is a little funky). It's just the timeline that bugs out.

From a glance, it appears to be because the numbers on the y-axis become super long. Perhaps try truncating them for large numbers.

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_{[original: nus-cs2103-AY1920S1/ped-interim#3048]}