refactor: remove usage of secp256r1 and demos

[shotexa]

Description:

Remove usage of secp256r1 in test sources and files used for demo of jwt creds in the past

Checklist:

• My PR follows the contribution guidelines of this project
• My PR is free of third-party dependencies that don't comply with the Allowlist
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked the PR title to follow the conventional commit specification

[github-actions]

Integration Test Results

14 files  ±0  14 suites  ±0   2s ⏱️ ±0s
30 tests ±0  30 ✅ ±0  0 💤 ±0  0 ❌ ±0 
33 runs  ±0  33 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 731e067. ± Comparison against base commit 975730a.

♻️ This comment has been updated with latest results.

[github-actions]

Unit Test Results

 90 files  ±0   90 suites  ±0   20m 26s ⏱️ +28s
759 tests ±0  751 ✅ ±0  8 💤 ±0  0 ❌ ±0 
766 runs  ±0  758 ✅ ±0  8 💤 ±0  0 ❌ ±0 

Results for commit 731e067. ± Comparison against base commit 975730a.

♻️ This comment has been updated with latest results.

[coveralls]

coverage: 51.74% (+2.4%) from 49.381%
when pulling 731e067 on ATL-7117-secp256r1-to-secp256k1
into 975730a on main.

[patlo-iog]

Small comment. The rest LGTM.

[shotexa]

Accidentally noticed it was not used by anything