chore(point-of-sale): update pos service response structure

[sanducb]

Changes proposed in this pull request

• This PR updates the response structure we return to the POS via POST /payment

Context

Closes #RAF-1175

Checklist

• Related issues linked using fixes #number
• Tests added/updated
• Make sure that all checks pass
• Bruno collection updated (if necessary)
• Documentation issue created with user-docs label (if necessary)
• OpenAPI specs updated (if necessary)

[github-actions]

🚀 Performance Test Results

Test Configuration:

• VUs: 4
• Duration: 1m0s

Test Metrics:

• Requests/s: 44.00
• Iterations/s: 14.70
• Failed Requests: 0.00% (0 of 2644)

📜 Logs

> [email protected] run-tests:testenv /home/runner/work/rafiki/rafiki/test/performance
> ./scripts/run-tests.sh -e test "-k" "-q" "--vus" "4" "--duration" "1m"

Cloud Nine GraphQL API is up: http://localhost:3101/graphql
Cloud Nine Wallet Address is up: http://localhost:3100/
Happy Life Bank Address is up: http://localhost:4100/
cloud-nine-wallet-test-backend already set
cloud-nine-wallet-test-auth already set
happy-life-bank-test-backend already set
happy-life-bank-test-auth already set
     data_received..................: 955 kB 16 kB/s
     data_sent......................: 2.0 MB 34 kB/s
     http_req_blocked...............: avg=7.2µs    min=2.29µs  med=5.34µs   max=978.13µs p(90)=6.52µs   p(95)=7.22µs  
     http_req_connecting............: avg=714ns    min=0s      med=0s       max=742.66µs p(90)=0s       p(95)=0s      
     http_req_duration..............: avg=90.26ms  min=6.27ms  med=73.18ms  max=714.81ms p(90)=149.35ms p(95)=192.34ms
       { expected_response:true }...: avg=90.26ms  min=6.27ms  med=73.18ms  max=714.81ms p(90)=149.35ms p(95)=192.34ms
     http_req_failed................: 0.00%  ✓ 0         ✗ 2644
     http_req_receiving.............: avg=94.92µs  min=22.06µs med=77µs     max=2.74ms   p(90)=118.45µs p(95)=164.31µs
     http_req_sending...............: avg=38.46µs  min=9.65µs  med=28.24µs  max=2.11ms   p(90)=41.54µs  p(95)=59.81µs 
     http_req_tls_handshaking.......: avg=0s       min=0s      med=0s       max=0s       p(90)=0s       p(95)=0s      
     http_req_waiting...............: avg=90.12ms  min=6.11ms  med=73.08ms  max=714.69ms p(90)=149.25ms p(95)=192.24ms
     http_reqs......................: 2644   44.003677/s
     iteration_duration.............: avg=271.95ms min=177.2ms med=252.46ms max=1.27s    p(90)=358.9ms  p(95)=399.59ms
     iterations.....................: 883    14.69563/s
     vus............................: 4      min=4       max=4 
     vus_max........................: 4      min=4       max=4 

[mkurapov]

We should the cleaning up of the map in a finally block