feat(dursto): define cfg aliases for test features at build time

[victor-dumitrescu]

Closes RV-1002.

What

Introduces 3 build-time cfg aliases:

• #[cfg(test_utils)] as an alias for #[cfg(feature = "unstable-test-utils")] (and also #[cfg(any(test, feature = "unstable-test-utils"))] because test always builds with the unstable-test-utils flag).
• #[cfg(rocksdb)] as an alias for #[cfg(feature = "rocksdb")]
• #[cfg(rocksdb_test_utils)] as an alias for #[cfg(all(feature = "unstable-test-utils", feature = "rocksdb"))]. This one is not yet used anywhere but will be used for the long tests binary.

Why

Simplifies cfg attributes, especially in test code.

How

As part of a newly introduced build script. All relevant attributes changed.

Manually Testing

make all

Tasks for the Author

• Link all Linear issues related to this MR using magic words (e.g. part of, relates to, closes).
• Eliminate dead code and other spurious artefacts introduced in your changes.
• Document new public functions, methods and types.
• Make sure the documentation for updated functions, methods, and types is correct.
• Add tests for bugs that have been fixed.
• Explain changes to regression test captures when applicable.
• Write commit messages in agreement with our guidelines.
• Self-review your changes to ensure they are high-quality.
• Complete all of the above before assigning this MR to reviewers.

[github-actions]

Benchmark results for revision 71e68c2:

Metric	Duration	TPS
Mean	1.495229601s	26.752
Worst	1.503893634s	26.598
Best	1.489122279s	26.861
Standard Deviation	±3.299943ms	±0.059

Full results

Run	Transfers	Duration	TPS
1	40	1.494855484s	26.758
2	40	1.492330271s	26.804
3	40	1.496961676s	26.721
4	40	1.498260096s	26.698
5	40	1.495359689s	26.749
6	40	1.503893634s	26.598
7	40	1.501966221s	26.632
8	40	1.496471472s	26.730
9	40	1.492277052s	26.805
10	40	1.493441962s	26.784
11	40	1.495716579s	26.743
12	40	1.495746888s	26.742
13	40	1.494459613s	26.766
14	40	1.489122279s	26.861
15	40	1.494020309s	26.773
16	40	1.492299329s	26.804
17	40	1.493917748s	26.775
18	40	1.493233905s	26.787
19	40	1.493010807s	26.792
20	40	1.497247001s	26.716

Compare the results above with those for the default branch.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.09%. Comparing base (6f5bc4b) to head (ad93f6f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1078   +/-   ##
=======================================
  Coverage   90.08%   90.09%           
=======================================
  Files         130      130           
  Lines       28355    28355           
  Branches    28355    28355           
=======================================
+ Hits        25545    25546    +1     
- Misses       2047     2048    +1     
+ Partials      763      761    -2     

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