branch-4.0: [fix](test) deflake several branch-4.0 P2 regression cases

[morningman]

What problem does this PR solve?

Deflake several pre-existing flaky/failing cases in the branch-4.0 P2 regression suite (surfaced by an internal P2 run). None of these are caused by product behavior changes.

1. opensky_p2count / avgDistance / totalDistance / mostBusyOrigin — backport of [fix](regression) fix p2 opensky failure #62447: the S3 source csv.gz was actually a tar.gz, so after it was corrected the loaded row count changed (+30 rows) while the committed .out still held the old values. Update the four .out files and re-enable the NumberTotalRows == NumberLoadedRows load assertion.

2. segcompaction_p2/test_segcompaction_agg_keys — backport of [fix](regression) Fix case test_segcompaction_agg_keys #61026: the AGGREGATE REPLACE winner for a duplicate key is not deterministic. S3 load parallelizes into segments whose boundaries are non-deterministic (adaptive memtable flush / memory pressure) and the read-merge keeps the first row by segment order, so which of the duplicate col_0=47 rows wins varies between runs. Assert exactly one row plus the value being one of the legitimate outcomes, and delete the brittle .out.

3. inverted_index_p2/test_show_data (test_show_data_with_compaction) — it compared index sizes with inverted_index_compaction_enable on vs off for exact equality. For identical data the on-disk size can differ slightly due to file/merge layout, so compare within a 10% tolerance instead, which still catches gross index bloat or corruption.

4. compaction/test_base_compaction_with_dup_key_max_file_size_limit — the test builds a specific rowset layout via manual compactions and expects a manual base compaction to be rejected with E-808 (input rowset exceeds base_compaction_dup_key_max_file_size_mbytes). When the BE global disable_auto_compaction is false, background compaction races the manual steps and reshapes the rowsets, and an in-test short-circuit masked the result. Disable auto compaction cluster-wide for the duration of the test (restored in finally) and assert on the real response.

5. compaction/test_single_replica_compaction — the waitForCompaction and getTabletStatus closures assigned code/out without def, which the regression framework's script-source guard rejects (defined global variables in script are not allowed: code). [fix](case) fix global vars used in cases #55933 declared only process; declare the remaining locals too.

Release note

None

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https://claude.ai/code/session_01QuX5zypeHzV1ZgT9o8BzoF

[hello-stephen]

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[morningman]

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