feat: hottier perf work

[de-sh]

Fixes #XXXX.

Description

• Uses FuturesUnordered to manage async tasks
• Reuses get_stream_path_for_date where possible
• Refactors human_size parsing
• Streams through results instead of collecting

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This PR has:

• been tested to ensure log ingestion and log query works.
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added documentation for new or modified features or behaviors.

[coveralls]

Pull Request Test Coverage Report for Build 12827274449

Details

• 0 of 199 (0.0%) changed or added relevant lines in 3 files are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.01%) to 12.785%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/handlers/http/logstream.rs	0	19	0.0%
src/utils/human_size.rs	0	42	0.0%
src/hottier.rs	0	138	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/migration/mod.rs	1	0.0%
src/hottier.rs	5	0.0%

Totals
Change from base Build 12823516428:	0.01%
Covered Lines:	2459
Relevant Lines:	19234

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💛 - Coveralls