Events addon: fix React keys warning

[Hypnosphi]

Issue: When using events addon, you get React warning about the keys, because events don't need to have id field as per docs

[codecov]

Codecov Report

Merging #3072 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #3072   +/-   ##
=======================================
  Coverage   36.08%   36.08%           
=======================================
  Files         438      438           
  Lines        9447     9447           
  Branches      875      907   +32     
=======================================
  Hits         3409     3409           
+ Misses       5498     5460   -38     
- Partials      540      578   +38

Impacted Files	Coverage Δ
addons/events/src/components/Panel.js	0% <0%> (ø)	⬆️
lib/ui/src/modules/ui/containers/addon_panel.js	23.52% <0%> (ø)	⬆️
addons/knobs/src/components/types/Boolean.js	11.62% <0%> (ø)	⬆️
...src/server/config/WatchMissingNodeModulesPlugin.js	0% <0%> (ø)	⬆️
lib/ui/src/modules/ui/containers/shortcuts_help.js	25% <0%> (ø)	⬆️
addons/a11y/src/components/Report/Info.js	0% <0%> (ø)	⬆️
app/react-native/src/bin/storybook-start.js	0% <0%> (ø)	⬆️
lib/ui/src/modules/ui/containers/stories_panel.js	27.02% <0%> (ø)	⬆️
addons/storysource/src/loader/generate-helpers.js	48.1% <0%> (ø)	⬆️
lib/ui/src/modules/ui/components/shortcuts_help.js	12.85% <0%> (ø)	⬆️
... and 56 more

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