🐛Traefik: partially revert changes

[sanderegg]

What do these changes do?

partially reverts #6257 which made the CORS error appear.
Also the 502 catch all was broken.

Related issue/s

How to test

Dev-ops checklist

• No ENV changes or I properly updated ENV (read the instruction)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.7%. Comparing base (cafbf96) to head (3c0c569).
Report is 482 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #6270      +/-   ##
=========================================
+ Coverage    84.5%   86.7%    +2.1%     
=========================================
  Files          10    1312    +1302     
  Lines         214   54643   +54429     
  Branches       25    1398    +1373     
=========================================
+ Hits          181   47384   +47203     
- Misses         23    7057    +7034     
- Partials       10     202     +192     

Flag	Coverage Δ
integrationtests	64.9% <ø> (?)
unittests	84.3% <ø> (-0.3%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ules/dynamic_sidecar/docker_service_specs/proxy.py	100.0% <ø> (ø)

... and 1261 files with indirect coverage changes