Debug client itinerary list style improvements

[a-limyr]

Summary

Update to the OTP Debug client.
Removed some spacing in the itinerary list to make the view more compact.

Issue

#5330 (comment)

This is to address the following:
UX - Less line spacing on expanded legs to make it easier to compare two itineraries.

The code is only some simple css and html changes to make the element more compact. See screenshots of before and after.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.73%. Comparing base (c3d1843) to head (5137512).
Report is 7 commits behind head on dev-2.x.

Additional details and impacted files

@@            Coverage Diff             @@
##             dev-2.x    #6012   +/-   ##
==========================================
  Coverage      69.73%   69.73%           
- Complexity     17313    17314    +1     
==========================================
  Files           1960     1960           
  Lines          74263    74267    +4     
  Branches        7603     7603           
==========================================
+ Hits           51790    51793    +3     
+ Misses         19832    19831    -1     
- Partials        2641     2643    +2     

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