Show two decimals on doughnutTooltip if total share shown is less than 1%

[yubiuser]

What does this PR aim to accomplish?:

If users hide a big part of the doughnut chart, rounding can lead to "falsely" reported item share and confuse users. See #2500.

To compensate for that, this PR will show two decimal precision of each tooltip item when the total shown percentage is less then 1%

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[yubiuser]

Has been confirmed working in #2500 (comment)

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-web-v5-18-2-and-core-v5-15-1-released/60695/1