Fix card add display bug

[awush-stripe]

Summary

Make sure the required card text does not show up for scans with no required card.

Motivation

The new card-add flow will display a required card: null without this change.

Testing

• Added tests
• Modified tests
• Manually verified

Changelog

[FIXED] 4575 Fix card add display bug

[github-actions]

Diffuse output:

OLD: paymentsheet-example-release-master.apk (signature: none)
NEW: paymentsheet-example-release-pr.apk (signature: none)

          │          compressed          │         uncompressed         
          ├───────────┬───────────┬──────┼───────────┬───────────┬──────
 APK      │ old       │ new       │ diff │ old       │ new       │ diff 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
      dex │    12 MiB │    12 MiB │  0 B │  40.7 MiB │  40.7 MiB │  0 B 
     arsc │   1.6 MiB │   1.6 MiB │  0 B │   1.6 MiB │   1.6 MiB │  0 B 
 manifest │   2.7 KiB │   2.7 KiB │  0 B │  11.1 KiB │  11.1 KiB │  0 B 
      res │ 697.8 KiB │ 697.8 KiB │  0 B │   1.1 MiB │   1.1 MiB │  0 B 
    asset │    78 KiB │    78 KiB │  0 B │ 109.5 KiB │ 109.5 KiB │  0 B 
    other │  78.3 KiB │  78.3 KiB │  0 B │   154 KiB │   154 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │  14.4 MiB │  14.4 MiB │  0 B │  43.7 MiB │  43.7 MiB │  0 B 

         │          raw           │           unique            
         ├────────┬────────┬──────┼────────┬────────┬───────────
 DEX     │ old    │ new    │ diff │ old    │ new    │ diff      
─────────┼────────┼────────┼──────┼────────┼────────┼───────────
   files │      3 │      3 │    0 │        │        │           
 strings │ 196168 │ 196168 │    0 │ 172484 │ 172484 │ 0 (+0 -0) 
   types │  33381 │  33381 │    0 │  31245 │  31245 │ 0 (+0 -0) 
 classes │  28840 │  28840 │    0 │  28840 │  28840 │ 0 (+0 -0) 
 methods │ 167676 │ 167676 │    0 │ 162675 │ 162675 │ 0 (+0 -0) 
  fields │ 122905 │ 122905 │    0 │ 122186 │ 122186 │ 0 (+0 -0) 

 ARSC    │ old  │ new  │ diff 
─────────┼──────┼──────┼──────
 configs │  298 │  298 │  0   
 entries │ 5394 │ 5394 │  0