Analytics: switch to using GA4 site tag only and UA via connected config

[chalin]

This is a followup to #1001 and #1003:

• Drop custom analytics layouts - Analytics: use GA4 tag only #1010
• Switch to using Docsy analytics feature - Analytics: use GA4 tag only #1010
• From GA4 site tag config, add the two existing UA site tags as connected IDs -->

  

• Confirm that GA4 site tag is still receiving data
• Confirm that UA-163836834-2 (CNCF site tag) is still receiving data
• Confirm that UA-60127042-1 (Google site tag) is still receiving data

[chalin]

We've reached our final analytics configuration for work done as part of the migration to GA4 (cncf/techdocs#108). I've confirmed that the CNCF GA4 and UA site tags are still receiving events. For example, this is the realtime overview page, 10 minutes after the new site deploy, for the CNCF UA property:

@thisisnotapril @ejona86 - I'm going to assume that the Google property (UA-60127042-1) is also still receiving events, and so close this issue. If that isn't the case, please reopen the issue so that I can investigate the problem.