perf: do thin LTO and singular `codegen-unit` on release

[de-sh]

Fixes #224 .

Description

Optimize release builds without impacting compile times. The alternatives include:

• Full/Fat LTO
• More codegen-units With single codegen-unit we make the compilation a bit slow, but that is much better tradeoff when compiling for releases given the optimizations that can be gained. Similarly, Fat LTO didn't give much of a gain from binary size perspective, have to figure out if there were any gains in terms of memory locality, but that is a harder question to answer, thus chose to go with Thin LTO.

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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.