Change response time chart "above the threshold" area fill color to #feedee.

Summary: Change background fill color from orange (#fce6dc), to pink (#feedee), to align with red threshold line color.

Rationale: The response time threshold line color was changed from what was orange to what is now red - for the purpose of better aligning with alerting colors. We use red to denote something bad has happened. Likewise the "Response Time (above the threshold)" background area fill should use some variant of red. Referring to color palette exercises, we had agree on using a pink #feedee color to go with a red line. The color currently used in the charts is #fce6dc and appears orange.