Add more GA events, fix clear uiFind & kbd modal

[everett980]

Which problem is this PR solving?

• Some user actions of interest were not being tracked, two user actions weren't being tracked correctly.

Short description of the changes

• Track keyboard shortcut modal open event on modal open, not on render.
• Track uiFind clear events caused by clicking clear button or hitting escape, not just when deleting all characters in input.
• • Do not track uiFind events when value is unchanged (e.g. spamming esc, or clicking blurring input without typing)
• Track trace timeline uiFind interactions (focus, next, prev)
• Track use of new Search Results Ddg

[codecov]

Codecov Report

Merging #470 into master will increase coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #470      +/-   ##
==========================================
+ Coverage   92.24%   92.31%   +0.07%     
==========================================
  Files         192      193       +1     
  Lines        4477     4492      +15     
  Branches     1071     1072       +1     
==========================================
+ Hits         4130     4147      +17     
+ Misses        305      303       -2     
  Partials       42       42

Impacted Files	Coverage Δ
.../components/SearchTracePage/SearchResults/index.js	80.76% <100%> (+0.76%)	⬆️
...jaeger-ui/src/components/TracePage/index.track.tsx	100% <100%> (ø)	⬆️
...racePage/TracePageHeader/KeyboardShortcutsHelp.tsx	95.83% <100%> (+8.33%)	⬆️
...kages/jaeger-ui/src/components/TracePage/index.tsx	100% <100%> (ø)	⬆️
...ents/SearchTracePage/SearchResults/index.track.tsx	100% <100%> (ø)
packages/jaeger-ui/src/utils/update-ui-find.tsx	100% <100%> (ø)	⬆️

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