Make fingerprinting faster

[rdner]

What does this PR do?

By using a buffer of the fingerprint's size. This descreases the amount of syscalls for reading the file.

Also added the benchmark for tracking the function's performance.

Benchmark results

Before (avg. ~22917 ns/op)

BenchmarkToFileDescriptor
BenchmarkToFileDescriptor-10               49345             23316 ns/op
BenchmarkToFileDescriptor-10               49766             23090 ns/op
BenchmarkToFileDescriptor-10               50439             22641 ns/op
BenchmarkToFileDescriptor-10               53368             22672 ns/op
BenchmarkToFileDescriptor-10               51948             22865 ns/op

After (avg. ~15501 ns/op)

BenchmarkToFileDescriptor
BenchmarkToFileDescriptor-10               68728             15549 ns/op
BenchmarkToFileDescriptor-10               75000             15558 ns/op
BenchmarkToFileDescriptor-10               73772             15575 ns/op
BenchmarkToFileDescriptor-10               74607             15134 ns/op
BenchmarkToFileDescriptor-10               76077             15690 ns/op

Performance gain is ~32%

Why is it important?

Who does not like performance improvements?

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
  - [ ] I have made corresponding changes to the documentation
  - [ ] I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
  - [ ] I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

How to test this PR locally

Related issues

• Related Add new fingerprint file identity #35734
• Related [Filebeat] Implement a more stable file identifier #34419

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @rdner? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2023-07-15T06:14:33.759+0000

• Duration: 70 min 2 sec

Test stats 🧪

Test	Results
Failed	0
Passed	8046
Skipped	757
Total	8803

💚 Flaky test report

Tests succeeded.

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[pchila]

LGTM