Change QualityMetrics lookback param to hours

[everett980]

Which problem is this PR solving?

• BE uses hours as a uint not lookback as a duration

Short description of the changes

• Change API request from /qualitymetrics-v2?service=${service}&lookback=${hours}h to /qualitymetrics-v2?service=${service}&hours=${hours}

[codecov]

Codecov Report

Merging #581 into master will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #581      +/-   ##
==========================================
- Coverage   93.55%   93.53%   -0.02%     
==========================================
  Files         217      217              
  Lines        5289     5289              
  Branches     1360     1360              
==========================================
- Hits         4948     4947       -1     
- Misses        300      301       +1     
  Partials       41       41              

Impacted Files	Coverage Δ
packages/jaeger-ui/src/api/jaeger.js	100.00% <100.00%> (ø)
.../jaeger-ui/src/components/QualityMetrics/index.tsx	91.42% <100.00%> (ø)
...eViewer/TimelineHeaderRow/TimelineViewingLayer.tsx	88.13% <0.00%> (-1.70%)	⬇️

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