test: fix flakiness in idle_tenure_extend_active_mining

[brice-stacks]

Tenure-change blocks (BlockFound/Extended) roll the timestamp over to now + idle_timeout, while regular blocks derive it from tenure start plus accumulated processing time. With second-level granularity these two formulas can produce equal timestamps, so only assert strict advancement between consecutive regular blocks (where the injected validation delay guarantees it advances). Skip the first block of each tenure and any tenure-change block.

[coveralls]

Coverage Report for CI Build 27151423578

Coverage increased (+0.1%) to 85.823%

Details

• Coverage increased (+0.1%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 7284 coverage regressions across 126 files.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

7284 previously-covered lines in 126 files lost coverage.

Top 10 Files by Coverage Loss	Lines Losing Coverage	Coverage
stackslib/src/config/mod.rs	376	68.96%
stackslib/src/net/mod.rs	310	78.05%
stackslib/src/chainstate/stacks/index/storage.rs	286	82.28%
clarity/src/vm/database/clarity_db.rs	268	82.11%
stackslib/src/chainstate/stacks/miner.rs	252	83.45%
stackslib/src/net/inv/epoch2x.rs	235	78.57%
stackslib/src/chainstate/stacks/db/transactions.rs	222	97.16%
stackslib/src/chainstate/nakamoto/mod.rs	203	84.75%
stackslib/src/net/chat.rs	199	93.05%
stackslib/src/chainstate/stacks/db/mod.rs	196	86.23%

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Coverage Stats

Relevant Lines:	224161
Covered Lines:	192381
Line Coverage:	85.82%
Coverage Strength:	18836571.17 hits per line

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💛 - Coveralls

[cylewitruk-stacks]

Makes sense 👍