Components: Remove focus return handling from Popover

[aduth]

Related: #2911, #2888

This pull request seeks to resolve an issue where it requires two subsequent tabs to move between buttons in the block toolbar. This is caused by the withFocusReturn applied to Popover forcefully moving focus back to a button after the tooltip is to be dismissed. With #2888 and #2911 the intended behavior of focus returns on toggle button popovers is now managed within the Dropdown component. If Popover were to need to manage this, it should at the very least be excluded on the basis of the focusOnOpen prop (which Tooltip explicitly sets as false).

Testing instructions:

Verify that tabbing through block toolbar options requires a single tab to move through buttons.
Verify there is no regressions in the behavior of focus return for Dropdown components (e.g. pressing escape while inserter is open should return focus to the inserter button).

[codecov]

Codecov Report

Merging #3056 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3056      +/-   ##
==========================================
+ Coverage   31.56%   31.59%   +0.03%     
==========================================
  Files         221      221              
  Lines        6311     6314       +3     
  Branches     1121     1122       +1     
==========================================
+ Hits         1992     1995       +3     
  Misses       3631     3631              
  Partials      688      688

Impacted Files	Coverage Δ
components/popover/detect-outside.js	25% <ø> (ø)	⬆️
components/popover/index.js	83.83% <100%> (+0.5%)	⬆️

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