Add % percentage indicator to standard deviation

[sumairq]

This PR adds a % percentage indicator to the standard deviation in compare view.

It is a solution for https://bugzilla.mozilla.org/show_bug.cgi?id=1831319.

[gmierz]

@sumairq one other thing we'll need to do is determine the number of standard deviations used in the percentage.

[sumairq]

@sumairq one other thing we'll need to do is determine the number of standard deviations used in the percentage.

The number of Standard deviations is located inside the tooltip before the percentage.

[gmierz]

@sumairq one other thing we'll need to do is determine the number of standard deviations used in the percentage.

The number of Standard deviations is located inside the tooltip before the percentage.

This gives the absolute size of the standard deviation, that said, I took a look and I'm unable to find us making any changes to the stddev before we display it so the %, and the number are equivalent to 1 standard deviation:

treeherder/ui/perfherder/compare/TableAverage.jsx

Line 30 in 15bae14

displayNumber(stddevpct),

I don't know where we can mention this though, any ideas @sumairq?

[gmierz]

Thinking about this further, we could do XX% for 1 standard deviation instead of XX% standard deviation