fix: disable allocator exclusion by default

[not-matthias]

No description provided.

[greptile-apps]

Greptile Summary

This PR disables allocator exclusion by default.

• Changes the shared run/exec exclude_allocations CLI default from true to false.
• Leaves explicit CLI and environment-variable overrides available.

Confidence Score: 4/5

The PR appears safe to merge, but its deprecated-option warning should be updated to describe the new allocator-exclusion default accurately.

The changed default flows consistently through run and exec, with the only accepted issue being stale user-facing guidance that still claims allocator exclusion defaults to true.

Files Needing Attention: src/cli/shared.rs and src/cli/experimental.rs

Important Files Changed

Filename	Overview
src/cli/shared.rs	Changes the allocator-exclusion default for both run and exec; the related deprecated-option warning still documents the previous default.

Prompt To Fix All With AI

### Issue 1
src/cli/shared.rs:129
**Stale allocator default guidance**

The deprecated `--experimental-exclude-allocations` warning still says allocator exclusion defaults to true, while this change makes the effective default false, giving users incorrect guidance when configuring benchmark measurements.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "fix: disable allocator exclusion by defa..." | Re-trigger Greptile}

[codspeed-hq]

Performance comparison unavailable

The base and head of this comparison were measured with different runner settings, so their benchmark values are not directly comparable.

What changed between base and head:

• Allocator-time exclusion (on → off) removes allocator time from the measurement, which shifts benchmark values. Learn more about allocator-time exclusion

Re-run the base with the same settings to get a valid performance comparison.

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_{Comparing cod-3301-fix-disable-allocator-exclusion-being-on-by-default (003bfb4) with main (0418479)}