[REF][Test] Update loadMappingTest to use form flow

[eileenmcnaughton]

Overview

[REF][Test] Update loadMappingTest to use form flow

Before

Test mimics parts of what the form does

After

Test tests what the form does - note the column numbers are fixed to start from 0 as they would be when submitted to avoid notices

Technical Details

Based on #23284 to avoid notices....

Comments

[civibot]

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[demeritcowboy]

jenkins retest this please

[demeritcowboy]

Needs rebase

Applying: Extract getContactType                                                         
  Patch failed at 0001 Extract getContactType                                              
  When you have resolved this problem, run "git am --continue".                            
  If you prefer to skip this patch, run "git am --skip" instead.                           
  To restore the original branch and stop patching, run "git am --abort".                  
  [[ STDERR ]]                                                                             
  error: patch failed: CRM/Contact/Import/Form/MapField.php:89                             
  error: CRM/Contact/Import/Form/MapField.php: patch does not apply                        
  error: patch failed: CRM/Contact/Import/MetadataTrait.php:103                            
  error: CRM/Contact/Import/MetadataTrait.php: patch does not apply                        
  error: patch failed: CRM/Contact/Import/Parser/Contact.php:261                           
  error: CRM/Contact/Import/Parser/Contact.php: patch does not apply                       
  error: patch failed: CRM/Import/Forms.php:293                                            
  error: CRM/Import/Forms.php: patch does not apply                                        
  error: patch failed: tests/phpunit/CRM/Contact/Import/Form/MapFieldTest.php:50           
  error: tests/phpunit/CRM/Contact/Import/Form/MapFieldTest.php: patch does not apply      
  error: patch failed: tests/phpunit/CiviTest/CiviUnitTestCase.php:3220                    
  error: tests/phpunit/CiviTest/CiviUnitTestCase.php: patch does not apply      

[eileenmcnaughton]

Rebased

[eileenmcnaughton]

thanks @demeritcowboy