Replace deterministic random values with actual randomness in tests

[bvkatwijk]

• Use random numbers instead of fixed sequence in loop

Two tests used identical fixed random instances inside a loop, causing the extact same sequence of numbers being generated:

        for (int i = 0; i < 10; i++) {
            final Random random = getRandom(123456789);
                // ...
                final int value = random.nextInt(size);
                // ...
        }

Each iteration will generate a fixed sequence (in this case: 2554, 3297, 4789, ...)
Unless I am missing the purpose, this means that each loop is identical and thus redundant.
Generating the same sequence of numbers via a Random does not seem to be the intented design here.

If my assumptions are correct, this fixes both issues by using an unseeded random instance, creating a test run with actual randomness.

If each loop iteration should be different but deterministic values are desired, a different fix could be to move the random instance out of the loop:

        final Random random = getRandom(123456789);
        for (int i = 0; i < 10; i++) {
                // ...
                final int value = random.nextInt(size);
                // ...
        }