PR: Remove white dots on IPython console tabbar for Windows

[ccordoba12]

Description of Changes

• I fixed this problem in PR: Improve style of the IPython console a bit #19297 for Linux but I noticed it's still present on Windows.

  Before

  

  After

  

• Remove unnecessary class constant.

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct:

[ccordoba12]

@mrclary, could you check if those white pixels are present or not on Mac with this PR? Thanks!

[mrclary]

@mrclary, could you check if those white pixels are present or not on Mac with this PR? Thanks!

macOS did not exhibit this issue before nor after this PR.

[mrclary]

Looks good to me! Thanks @ccordoba12.

[dalthviz]

Thanks @ccordoba12 ! Checked locally but I still see a white dot on Windows:

Also, just in case, running with the latest 5.x I can see three dots:

[ccordoba12]

Checked locally but I still see a white dot on Windows

Ok, that glitch is almost unnoticeable in my machine but it's clearly in yours, so I'll fix it too.

[ccordoba12]

@dalthviz, I think I fixed the last white dot in my last commit, so please check again.

[dalthviz]

@ccordoba12 still seeing it with the latest changes:

Also, playing a little bit with the IPython console dockwidget seems like the white dot dissapears when the tabs need to be collapsed and the tab buttons to horizontally scroll appear and take place on top of the tab list button:

[ccordoba12]

@mrclary, could you recheck that you're not seeing white dots on Mac with this PR? My last commit could have changed things there (hopefully not, but you never know).

[dalthviz]

Thanks @ccordoba12 !

[mrclary]

I confirm no white dots on macOS with latest commit