[FW][FIX] mail: overlapping activity counter badge

[fw-bot]

Steps to reproduce:

• Go to activity view. (Ensure that it has at least 10-12 activity types)
• Schedule multiple activities for the same day.
• Activity count badge overlaps activity deadline!

Before this PR:
Activity count badge overlaps the activity deadline in an activity cell.

After this PR:
The issue has been resolved by tweaking the CSS of Activity Cell.

Task-3818264

Forward-Port-Of: #162573
Forward-Port-Of: #158512

[robodoo]

Pull request status dashboard.

[fw-bot]

@khpa-odoo @tde-banana-odoo cherrypicking of pull request #158512 failed.

stdout:

Auto-merging addons/mail/static/src/views/web/activity/activity_cell.xml
CONFLICT (content): Merge conflict in addons/mail/static/src/views/web/activity/activity_cell.xml

stderr:

10:46:18.212811 git.c:463               trace: built-in: git cherry-pick b8feb4fae2083320e46e3e9a9f02946037c89b0d
error: could not apply b8feb4fae208... [FIX] mail: overlapping activity counter badge
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
----------
status:

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

⚠️ after resolving this conflict, you will need to merge it via @robodoo.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[khpa-odoo]

@tde-banana-odoo Hello : )
I believe the issue in question won't be faced from 17.0 onwards...
So I think we can close this PR. WDYT?