Bug 1499551 - Fix accumulating window event-listener leaks (part 1/3)

[camd]

Part 1 of 3 addressing Bug 1499551 (jobs-view memory/CPU growth over time).

Two class components added a window event listener with an anonymous handler and no componentWillUnmount, so each mount permanently accumulated a listener (and its captured component instance):

• FailureSummaryTab (internalIssueClassification) — remounts on every job selection.
• GraphsContainer (resize) — remounts on every test/time-range change.

Both now store the handler as a stable class-property arrow and remove that same reference on unmount. GraphsContainer's resize handler recomputes zoomDomain from current scatterPlotData (via the existing initZoomDomain) instead of capturing a stale mount-time value.

Independent of the other two Bug 1499551 PRs.

Testing

• New unit tests assert the same handler reference is removed on unmount.
• Full frontend unit suite passes; lint clean.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 80.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.67%. Comparing base (6a820e6) to head (f43671f).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
ui/perfherder/graphs/GraphsContainer.jsx	80.00%	1 Missing ⚠️
...i/shared/tabs/failureSummary/FailureSummaryTab.jsx	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #9704    +/-   ##
========================================
  Coverage   82.66%   82.67%            
========================================
  Files         626      626            
  Lines       36753    36757     +4     
  Branches     3348     3276    -72     
========================================
+ Hits        30383    30389     +6     
- Misses       5988     6218   +230     
+ Partials      382      150   -232     

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