chore: override toString methods in records

[Grigorov-Georgi]

Description:

Override the default toString() in SchnorrKeyPair and TssKeyPair records to output only its public key.

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[lfdt-bot]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@             Coverage Diff              @@
##               main   #26817      +/-   ##
============================================
- Coverage     70.50%   70.50%   -0.01%     
  Complexity    11691    11691              
============================================
  Files          2587     2587              
  Lines        108453   108456       +3     
  Branches      12142    12141       -1     
============================================
- Hits          76469    76464       -5     
- Misses        27994    28005      +11     
+ Partials       3990     3987       -3     

Files with missing lines	Coverage Δ	Complexity Δ
...a/node/app/history/impl/ProofKeysAccessorImpl.java	95.12% <100.00%> (+0.12%)	0.00 <0.00> (ø)
...main/java/com/hedera/node/app/tss/TssKeyFiles.java	76.99% <100.00%> (+0.20%)	0.00 <0.00> (ø)
.../main/java/com/hedera/node/app/tss/TssKeyPair.java	100.00% <100.00%> (ø)	0.00 <0.00> (ø)

... and 9 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[joshmarinacci]

please check the failling hapi test. Probably a flak.

[testlens-app]

✅ All tests passed ✅

🏷️ Commit: 4f06cee
▶️ Tests: 52542 executed
⚪️ Checks: 33/33 completed

---

Learn more about TestLens at testlens.app.

[andrewb1269]

All checks pass on #26860 so merging this PR.