test: randomize perturbed files excluding ldb

[L0laL33tz]

As discussed in #28831 the ldb files are too small to be randomized for pertubation. This PR excludes ldb files from randomization. Blockfiles are randomly perturbed, ldb file pertubation remains deterministic. For additional rationale see #28612

[DrahtBot]

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #29034 (test: detect OS in functional tests consistently using platform.system() by theStack)

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[maflcko]

Please keep your fixup commits squashed according to https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md#squashing-commits

[maflcko]

are block files guaranteed to contain this many bytes of blocks, always?

[L0laL33tz]

I tested this the same way @fjahr tested the size of the ldb files in #28831 with

                self.log.info(f"Perturbing file to ensure failure {target_file}, size: {os.path.getsize(target_file)}")

The tested blockfile should always have 16777216 bytes

[kevkevinpal]

I tested this by creating a loop similar to how @maflcko found an issue in #28831

I also noticed that in this test we only perturbed one blk?????.dat file which is blk00000.dat
Should we add another .dat file to test this on?

[DrahtBot]

🐙 This pull request conflicts with the target branch and needs rebase.

[DrahtBot]

⌛ There hasn't been much activity lately and the patch still needs rebase. What is the status here?

• Is it still relevant? ➡️ Please solve the conflicts to make it ready for review and to ensure the CI passes.
• Is it no longer relevant? ➡️ Please close.
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[maflcko]

Closing for now, but feel free to open a new pull request, with the changes rebased.