Hardcode LegacyEphemeralKey and CustomerSession invariants as class-body overrides

[cttsai-stripe]

Summary

• Moved structurally invariant fields from constructor parameters to hardcoded class-body overrides in CustomerMetadata.LegacyEphemeralKey and CustomerMetadata.CustomerSession
• LegacyEphemeralKey: removePaymentMethod (always Full), saveConsent (always Legacy), and canUpdateFullPaymentMethodDetails (always false) are now body overrides instead of constructor params
• CustomerSession: canUpdateFullPaymentMethodDetails (always true) is now a body override instead of a constructor param
• Updated createForCustomerSheet factory to align — the LegacyEphemeralKey branch now only passes id, ephemeralKeySecret, isPaymentMethodSetAsDefaultEnabled, and canRemoveLastPaymentMethod
• Updated all test call sites (12 files) to remove the now-hardcoded parameters

These values were already invariant in production — both the PaymentSheet and CustomerSheet paths always produced the same values for these fields. Making them structural enforces correctness and simplifies construction.

Follows the same pattern established for CheckoutSession in #12581.

Test plan

• ./gradlew :paymentsheet:compileDebugKotlin :paymentsheet:compileDebugUnitTestKotlin passes

🤖 Generated with Claude Code

[github-actions]

Diffuse output:

OLD: identity-example-release-base.apk (signature: V1, V2)
NEW: identity-example-release-pr.apk (signature: V1, V2)

          │          compressed          │         uncompressed         
          ├───────────┬───────────┬──────┼───────────┬───────────┬──────
 APK      │ old       │ new       │ diff │ old       │ new       │ diff 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
      dex │   2.2 MiB │   2.2 MiB │  0 B │   4.6 MiB │   4.6 MiB │  0 B 
     arsc │   1.2 MiB │   1.2 MiB │  0 B │   1.2 MiB │   1.2 MiB │  0 B 
 manifest │   2.3 KiB │   2.3 KiB │  0 B │     8 KiB │     8 KiB │  0 B 
      res │   298 KiB │   298 KiB │  0 B │ 447.6 KiB │ 447.6 KiB │  0 B 
   native │  18.6 MiB │  18.6 MiB │  0 B │  18.6 MiB │  18.6 MiB │  0 B 
    asset │   7.9 KiB │   7.9 KiB │  0 B │   7.6 KiB │   7.6 KiB │  0 B 
    other │ 110.3 KiB │ 110.3 KiB │ -1 B │ 237.3 KiB │ 237.3 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │  22.4 MiB │  22.4 MiB │ -1 B │    25 MiB │    25 MiB │  0 B 

 DEX     │ old   │ new   │ diff      
─────────┼───────┼───────┼───────────
   files │     1 │     1 │ 0         
 strings │ 22028 │ 22028 │ 0 (+0 -0) 
   types │  6586 │  6586 │ 0 (+0 -0) 
 classes │  5315 │  5315 │ 0 (+0 -0) 
 methods │ 32247 │ 32247 │ 0 (+0 -0) 
  fields │ 18592 │ 18592 │ 0 (+0 -0) 

 ARSC    │ old  │ new  │ diff 
─────────┼──────┼──────┼──────
 configs │  158 │  158 │  0   
 entries │ 3979 │ 3979 │  0

APK

   compressed    │   uncompressed   │                        
──────────┬──────┼───────────┬──────┤                        
 size     │ diff │ size      │ diff │ path                   
──────────┼──────┼───────────┼──────┼────────────────────────
 29.3 KiB │ -2 B │    65 KiB │  0 B │ ∆ META-INF/CERT.SF     
 25.8 KiB │ +2 B │  64.9 KiB │  0 B │ ∆ META-INF/MANIFEST.MF 
  1.2 KiB │ -1 B │   1.2 KiB │  0 B │ ∆ META-INF/CERT.RSA    
──────────┼──────┼───────────┼──────┼────────────────────────
 56.3 KiB │ -1 B │ 131.1 KiB │  0 B │ (total)