Fixed display of session info on tab

[srirambv]

Test Plan:

• Open new session tab
• Click on a target="_blank" link
• New tab should have only numbers and not partition- string on its tab

#7741 (comment)

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Original issue description

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

• Describe the issue you encountered:
  Partition text for session tab is overlapping on the tab title

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

• Brave Version (revision SHA):
  Brave 0.14.0
  rev 7dfeeb0

• Steps to reproduce:

  1. Do a clean install of 0.14.0
  2. Visit a site in a new session tab
  3. Open a link in new tab from the session tab
  4. The text partition is overlapping on the tab title (see screenshot)

• Actual result:
  Partition text for session tab is overlapping on the tab title

• Expected result:
  Should not over lap on tab title

• 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?
  N/A

• Can this issue be consistently reproduced?
  Yes

• Extra QA steps:
  1.
  2.
  3.

• Screenshot if needed:
  

• Any related issues:

[alexwykoff]

This is the current expectation, where purple only shows for the active private tab. Future design will have a purple hint for inactive tabs.