fix: LEAP-14: Fixes for New Taxonomy

[hlomzik]

• submitted values displayed after load with 5452 FF on
• per-region values are displayed with 5452 FF on
• fix API root item: object with items instead of plain array of items
• support leafsOnly param

PR fulfills these requirements

• Commit message(s) and PR title follows the format [fix|feat|ci|chore|doc]: TICKET-ID: Short description of change made ex. fix: DEV-XXXX: Removed inconsistent code usage causing intermittent errors
• Tests for the changes have been added/updated (for bug fixes/features)
• Docs have been added/updated (for bug fixes/features)
• Best efforts were made to ensure docs/code are concise and coherent (checked for spelling/grammatical errors, commented out code, debug logs etc.)
• Self-reviewed and ran all changes on a local instance (for bug fixes/features)

Describe the reason for change

Critical issues

What feature flags were used to cover this change?

Problems appeared only with fflag_feat_front_lsdv_5452_taxonomy_labeling_110823_short on

Does this PR introduce a breaking change?

• Yes, and covered entirely by feature flag(s)
• Yes, and covered partially by feature flag(s)
• No
• Not sure (briefly explain the situation below)

What level of testing was included in the change?

(check all that apply)

• e2e
• integration
• unit

Which logical domain(s) does this change affect?

Async Taxonomy, Taxonomy Labeling

[codecov-commenter]

Codecov Report

Patch coverage: 18.18% and project coverage change: -0.04% ⚠️

Comparison is base (999a946) 68.04% compared to head (aad0b31) 68.01%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1537      +/-   ##
==========================================
- Coverage   68.04%   68.01%   -0.04%     
==========================================
  Files         442      442              
  Lines       28231    28235       +4     
  Branches     7481     7483       +2     
==========================================
- Hits        19209    19203       -6     
- Misses       7790     7797       +7     
- Partials     1232     1235       +3     

Files Changed	Coverage Δ
src/tags/control/Taxonomy/Taxonomy.js	71.64% <14.28%> (-1.09%)	⬇️
src/components/NewTaxonomy/NewTaxonomy.tsx	11.11% <25.00%> (-0.66%)	⬇️

... and 1 file with indirect coverage changes

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