Editing autocompleted URL deletes autocompleted URL with typed in key

[srirambv]

• Did you search for similar issues before submitting this one?
  Yes

• Describe the issue you encountered:
  Editing autocompleted URL deletes a portion of the URL text

• Platform (Win7, 8, 10? macOS? Linux distro?):
  Windows x64

• Brave Version (revision SHA):
  Brave 0.16.4
  rev 15d8d36
  Muon 4.0.0

• Steps to reproduce:

  1. Visit https://github.com/brave/browser-laptop/issues/ in a tab
  2. Open new tab and type in git for history to come up
  3. Select the suggested history item and select laptop and type i. entire text is replaced and retains giti

• Actual result:
  Editing autocompleted URL deletes a portion of the URL text

• Expected result:
  Should only replace text and not remove entire URL

• Will the steps above reproduce in a fresh profile? If not what other info can be added?
  Yes

• Is this an issue in the currently released version?
  Yes from 0.15.310 onwards(post bloodhound URL PR Bloodhound for URL bar suggestions & move suggestions to browser process #8824 )

• Can this issue be consistently reproduced?
  Yes

• Extra QA steps:
  1.
  2.
  3.

• Screenshot if needed:
  

• Any related issues:
  cc: @bbondy

[bsclifton]

Automated test covers this very well (as long as we check results before deploying); marking as no-qa-needed