Stage vs. Discharge Plot - Fix Peak Data not showing up without USGS Rating Curve or USGS Measured

[maggiejaenicke]

These plots should still show the annual peaks even though there are no measurements, but no data is appearing:

• Plot 06326510 has peak data (this.formattedDischargePeakDates), but no USGS Rating Curve data (this.dischargeObj) or USGS Measured Discharge data (this.measuredObj).

• Plot 13234300 has peak data and USGS Measured data (but looks like all y values are NaN/empty), but not a USGS Rating Curve.

• NaN values are currently included in y, both in USGS Measured and peaks. Could be solved by filtering these out, similar to how this is handled for the Annual Peak Flow Plot in the formatData() function: if(!isNaN(.....)) {}

• Fix plots where data (that exists) doesn't show up

Replaces item in #1708

[amedenblik]

May be resolved with #1925