storcon: allow for more concurrency in drain/fill operations

[VladLazar]

Problem

We saw the drain/fill operations not drain fast enough in ap-southeast.

Summary of changes

These are some quick changes to speed it up:

• double reconcile concurrency - this is now half of the available reconcile bandwidth
• reduce the waiter polling timeout - this way we can spawn new reconciliations faster

[github-actions]

7716 tests run: 7397 passed, 0 failed, 319 skipped (full report)

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Flaky tests (8)

Postgres 17

• test_nbtree_pagesplit_cycleid: release-arm64
• test_idle_checkpoints: debug-x86-64
• test_scrubber_physical_gc_ancestors[None]: release-arm64
• test_check_visibility_map: debug-x86-64, debug-x86-64

Postgres 16

• test_pageserver_gc_compaction_smoke: release-x86-64
• test_pgdata_import_smoke[None-1024-RelBlockSize.MULTIPLE_RELATION_SEGMENTS]: release-arm64

Postgres 14

• test_physical_replication_config_mismatch_max_locks_per_transaction: release-x86-64

Code coverage* (full report)

• functions: 31.4% (8342 of 26534 functions)
• lines: 47.7% (65726 of 137710 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
1940d8c at 2024-12-11T19:47:49.879Z :recycle:}