feat: make samply profiler default for all OSes (#472)

[GuillaumeLagrange]

Previously merged with #472, but it got "reverted" because of force push

[greptile-apps]

Greptile Summary

Makes Samply the default wall-time profiler on every supported OS.

• Adds an internal executable override so profiler subprocesses can re-enter the CodSpeed CLI reliably.
• Runs wall-time and memory executor tests without the previous CI-only gate and builds required workspace binaries on demand.
• Updates the Samply submodule and removes redundant CI installation and build-script logic.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
src/executor/wall_time/executor.rs	Changes the implicit wall-time profiler from platform-specific selection to Samply on all operating systems.
src/cli/mod.rs	Adds an environment-variable override for the executable used to dispatch internal Samply subcommands.
src/executor/tests.rs	Makes executor tests self-contained by building and explicitly selecting the required workspace binaries.
Cargo.toml	Adds Escargot as a development dependency for locating binaries built during tests.
.github/workflows/ci.yml	Removes the now-redundant explicit exec-harness installation step.

Sequence Diagram

sequenceDiagram
    participant Executor as WallTimeExecutor
    participant Profiler as SamplyProfiler
    participant CLI as CodSpeed internal CLI
    participant Benchmark
    Executor->>Profiler: Select default profiler
    Profiler->>CLI: Re-exec CODSPEED_SELF_EXE samply
    CLI->>Benchmark: Record benchmark process
    Benchmark-->>Profiler: Profiling data
    Profiler-->>Executor: Finalized wall-time artifacts

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_{Reviews (2): Last reviewed commit: "feat: make samply profiler default for a..." | Re-trigger Greptile}

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 17 untouched benchmarks

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_{Comparing cod-2796-switch-to-samply-profiler-by-default (266f658) with main (97a789a)}

[GuillaumeLagrange]

@greptileai review