ci: find optimal number of runs for fuzz/invariant tests

[zugdev]

Resolves #943

[zugdev]

You can check at my fork's actions. That in branch optimal-fuzz-invariant-runs I've achieved:

Deep Fuzz (~5h30m) with 16,500,000 runs

1. Job Run 1 - 5h 14m 03s
2. Job Run 2 - 5h 28m 16s
3. Job Run 3 - 5h 29m 31s
4. Job Run 4 - 5h 30m 05s
5. Job Run 5 - 5h 31m 02s

Invariant Tests (~5h40m) with 350,000 runs

1. Job Run 1 - 5h 38m 49s
2. Job Run 2 - 5h 37m 39s
3. Job Run 3 - 5h 39m 05s
4. Job Run 4 - 5h 39m 20s
5. Job Run 5 - 5h 41m 10s

[ubiquity-os-deployer]

6c25a2d