Excessive execution time in LtByXslTest needs reduction

[0pdd]

The puzzle 870-2650a22a from #870 has to be resolved:

lints/src/test/java/org/eolang/lints/LtByXslTest.java

Lines 52 to 58 in b2d15a1

	* @todo #870:90min Reduce total execution time of LtByXslTest below 60 seconds.
	* The full test suite in this class takes ~197 seconds to run (360 tests), which
	* is too slow for a regular build. Investigate which parameterized or integration
	* tests dominate the runtime (likely {@code testsAllLintsByEo} and similar
	* classpath-scanning suites), and consider splitting heavy tests into a separate
	* integration-test profile, parallelising test execution, or caching parsed XMIR
	* across test cases where it is safe to do so.

The puzzle was created by @volodya-lombrozo on 20-May-26.

Estimate: 90 minutes, role: DEV.

If you have any technical questions, don't ask me, submit new tickets instead. The task will be "done" when the problem is fixed and the text of the puzzle is removed from the source code. Here is more about PDD and about me.

[0pdd]

@0pdd the puzzle #879 is still not solved.

[sherenkov]

@yegor256 @volodya-lombrozo can I take this one? Plan: tag the slow parameterized
tests in LtByXslTest with @Tag("deep") (matching the existing pattern in the
same file) so they continue running via the deep.yml workflow but drop out of
the default mvn test.

[volodya-lombrozo]

@sherenkov I have aleady solved it here: #878 just forgot to remove this puzzle

[0pdd]

@0pdd the only puzzle #879 is solved here.