KNOX-3370: Eliminate deprecated TokenStateService implementations

[smolnar82]

KNOX-3370 - Eliminate deprecated TokenStateService implementations

What changes were proposed in this pull request?

Removed deprecated TSS implementations as agreed in this DISCUSS thread.

How was this patch tested?

Built Knox and ran integration tests locally.
I also checked if TokenMigrationTool still works:

2026-07-01 12:00:50,126  INFO  knox.gateway (AbstractGatewayServices.java:start(60)) - Starting service: org.apache.knox.gateway.services.token.impl.DerbyDBTokenStateService
2026-07-01 12:00:50,127  INFO  token.state (TokenMigrationTool.java:log(116)) - Loading token aliases from the __gateway credential store. This could take a while.
2026-07-01 12:00:50,195  INFO  token.state (TokenMigrationTool.java:log(116)) - Token aliases loaded in 68 milliseconds
2026-07-01 12:00:50,195  INFO  token.state (TokenMigrationTool.java:log(116)) - Processed 0 tokens in 0 milliseconds
2026-07-01 12:00:50,195  INFO  token.state (TokenMigrationTool.java:log(116)) - Removing token aliases from the __gateway credential store...
2026-07-01 12:00:50,196  INFO  token.state (TokenMigrationTool.java:log(116)) - Removed token related aliases from the __gateway credential store in 1 milliseconds

Integration Tests

N/A

UI changes

N/A

[github-actions]

Test Results

32 tests   32 ✅  3s ⏱️
 1 suites   0 💤
 1 files     0 ❌

Results for commit 425e863.