feat: Parallelize event page fetch

[iamareebjamal]

Fetch infos about tickets, speakers, sessions, etc parallely.
Should be ideally done in their own components but OK for now
Also include event and tickets in discount code query

Fix for #4099

[vercel]

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[codecov]

Codecov Report

Merging #4400 into development will decrease coverage by 0.02%.
The diff coverage is 0.00%.

@@               Coverage Diff               @@
##           development    #4400      +/-   ##
===============================================
- Coverage        22.63%   22.61%   -0.03%     
===============================================
  Files              468      468              
  Lines             4943     4949       +6     
  Branches             6        6              
===============================================
  Hits              1119     1119              
- Misses            3823     3829       +6     
  Partials             1        1              

Impacted Files	Coverage Δ
app/components/public/ticket-list.js	17.69% <0.00%> (ø)
app/routes/public/index.js	0.00% <0.00%> (ø)

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