Libc-dbg install triggers despite cache restore

[GuillaumeLagrange]

Instead of relying on dpkg to determine if debug symbols are installed, simply look for them in the expected debian based places. This is quite fragile, and will be solved once we internalize the well-known library's debug infos through debug info servers in the backend, but at least it will prevent reinstallation of valgrind and libc debug on every run.

Tested in https://github.com/CodSpeedHQ/codspeed/actions/runs/32247794511/job/96052014667#step:5:36 (debug logs were activated for this run)

Closes #504

[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-3306-fix-instruments-cache-behavior-in-the-action (bebb031) with main (3798897)}

[greptile-apps]

Greptile Summary

The PR replaces the dpkg package-state check with direct discovery of libc's separate debug information, preventing restored cache contents from triggering redundant package installation.

• Moves shared build-id and .gnu_debuglink discovery into executor::helpers::debug_file.
• Uses the shared lookup to determine whether libc debug symbols are available before installing Valgrind dependencies.
• Updates perf symbolication consumers and tests to use the relocated helper.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete changed-code failure identified on the supported Valgrind targets.

The shared debug-file lookup preserves the prior perf behavior, and the new setup predicate targets the same x86_64 and aarch64 Debian/Ubuntu environments supported by the Valgrind installer.

Important Files Changed

Filename	Overview
src/executor/valgrind/setup.rs	Replaces the libc6-dbg package-state check with debug-file discovery for the supported Debian/Ubuntu architectures.
src/executor/helpers/debug_file.rs	Centralizes build-id and CRC-validated .gnu_debuglink lookup previously located in the perf ELF helper.
src/executor/helpers/apt.rs	Removes the now-unused dpkg -s package-state helper.
src/executor/wall_time/profiler/perf/debug_info.rs	Switches perf debug-info loading to the shared debug-file helper without changing lookup behavior.
src/executor/wall_time/profiler/perf/elf_helper.rs	Removes debug-file lookup code after its relocation to the executor helper module.
src/executor/wall_time/profiler/perf/module_symbols.rs	Switches separate symbol-table discovery and associated tests to the shared helper.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[Valgrind setup] --> B{Valgrind installed?}
  B -- No --> E[Restore or install packages]
  B -- Yes --> C[Resolve system libc path]
  C --> D{Build-id or debuglink file found?}
  D -- Yes --> F[Skip package installation]
  D -- No --> E

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