Fixes parsing of chained OR/AND conditions in input rules

What does this MR do and why?

Fixes parsing of chained OR/AND conditions in input rules by flattening consecutive operations of the same type into a single level.

Problem: Chained conditions like A || B || C || D were being parsed as nested binary trees instead of flat arrays.

Changelog: fixed

Fixed: #584832 (closed)

How to reproduce

1. Create a .gitlab-ci.yml with chained OR conditions:

   spec:
     inputs:
       main_selector:
         default: "Undefined"
         options: 
           - "Undefined"
           - "Choice 1"
           - "Choice 2"
           - "Choice 3"
           - "Choice 4"
           - "Choice 5"
           - "Choice 6"
       param_123:
         rules:
           - if: $[[inputs.main_selector]] == "Choice 1" || $[[inputs.main_selector]] == "Choice 2" || $[[inputs.main_selector]] == "Choice 3"
             default: "Value A"
             options: [ "Value A" ]
       param_456:
         rules:
           - if: $[[inputs.main_selector]] == "Choice 4" || $[[inputs.main_selector]] == "Choice 5" || $[[inputs.main_selector]] == "Choice 6"
             default: "Value B"
             options: [ "Value B" ]
       param_123456:
         rules:
           - if: $[[inputs.main_selector]] == "Choice 1" || $[[inputs.main_selector]] == "Choice 2" || $[[inputs.main_selector]] == "Choice 3" || $[[inputs.main_selector]] == "Choice 4" || $[[inputs.main_selector]] == "Choice 5" || $[[inputs.main_selector]] == "Choice 6"
             default: "Value C"
             options: [ "Value C" ]
       param_123456_2x3:
         rules:
           - if: ( $[[inputs.main_selector]] == "Choice 1" || $[[inputs.main_selector]] == "Choice 2" || $[[inputs.main_selector]] == "Choice 3" ) || ( $[[inputs.main_selector]] == "Choice 4" || $[[inputs.main_selector]] == "Choice 5" || $[[inputs.main_selector]] == "Choice 6" )
             default: "Value C"
             options: [ "Value C" ]
       param_123456_3x2:
         rules:
           - if: ( $[[inputs.main_selector]] == "Choice 1" || $[[inputs.main_selector]] == "Choice 2" ) || ( $[[inputs.main_selector]] == "Choice 3" || $[[inputs.main_selector]] == "Choice 4" ) || ( $[[inputs.main_selector]] == "Choice 5" || $[[inputs.main_selector]] == "Choice 6" )
             default: "Value C"
             options: [ "Value C" ]
   
   ---
   
   info:
     script: |
       echo 'main_selector = $[[inputs.main_selector]]'
       echo 'param_123 = $[[inputs.param_123]]'
       echo 'param_456 = $[[inputs.param_456]]'
       echo 'param_123456 = $[[inputs.param_123456]]'
       echo 'param_123456_2x3 = $[[inputs.param_123456_2x3]]'
       echo 'param_123456_3x2 = $[[inputs.param_123456_3x2]]'
   

The values should be as follows in the UI:

  main_selector = "Undefined":
  - Nothing appears (no inputs show up)

  main_selector = "Choice 1":
  - param_123 (Value A)
  - param_123456 (Value C) ← KEY TEST
  - param_123456_2x3 (Value C)
  - param_123456_3x2 (Value C)

  main_selector = "Choice 2":
  - param_123 (Value A)
  - param_123456 (Value C) ← KEY TEST
  - param_123456_2x3 (Value C)
  - param_123456_3x2 (Value C)

  main_selector = "Choice 3":
  - param_123 (Value A)
  - param_123456 (Value C) ← KEY TEST
  - param_123456_2x3 (Value C)
  - param_123456_3x2 (Value C)

  main_selector = "Choice 4":
  - param_456 (Value B)
  - param_123456 (Value C) ← KEY TEST
  - param_123456_2x3 (Value C)
  - param_123456_3x2 (Value C)

  main_selector = "Choice 5":
  - param_456 (Value B)
  - param_123456 (Value C) ← KEY TEST
  - param_123456_2x3 (Value C)
  - param_123456_3x2 (Value C)

  main_selector = "Choice 6":
  - param_456 (Value B)
  - param_123456 (Value C) ← KEY TEST
  - param_123456_2x3 (Value C)
  - param_123456_3x2 (Value C)

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