MWPW-162305: [Black Friday] CTA not visible on CRM due to sticky banner

[mirafedas]

Increasing z-index for .commerce-frame modals and modal curtains to overlap the promo banner.
The issue with modal URLs is fixed in this related CC PR: adobecom/cc#450 .

Resolves: MWPW-162305

Test URLs:

• Before: https://main--cc--adobecom.hlx.page/ca/products/aftereffects?instant=2024-11-15T14:00:00.000Z
• After: https://mwpw-162305-modal-sticky-banner --cc--adobecom.hlx.page/ca/products/aftereffects?milolibs=mwpw-162305-modal-sticky-banner--milo--mirafedas&instant=2024-11-15T14:00:00.000Z
  (Added spaces after branch name to make links invisible for PSI check, this change does not influence performance)
  For PSI check:
  https://mwpw-162305-modal-sticky-banner--milo--mirafedas.hlx.live?martech=off&georouting=off

[aem-code-sync]

	Page	Scores	Audits	Google
📱	/?martech=off&georouting=off
🖥️	/?martech=off&georouting=off

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.83%. Comparing base (343ba6e) to head (6e5509a).
Report is 2 commits behind head on stage.

Additional details and impacted files

@@            Coverage Diff             @@
##            stage    #3188      +/-   ##
==========================================
+ Coverage   96.37%   98.83%   +2.45%     
==========================================
  Files         245       70     -175     
  Lines       56598     8573   -48025     
==========================================
- Hits        54548     8473   -46075     
+ Misses       2050      100    -1950     

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