refactor(availability/light): remove samples amount settings

[walldiss]

The setting was allowing users to change amount of samples for light availability. The ability to set the value only causes users to misuse the setting:

• setting value lower than 16 screws security guaranties of DASing
• setting value higher than default consumes more resources of light node, while gain of security is minimal. It would cause unnecessary overhead for light node.

Node can define hardcoded value, which should be part of protocol defined values for light nodes. From code perspective, hardcoded value and removal of settings will simplify the code of light availability as well as configuration options.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 45.13%. Comparing base (2469e7a) to head (1756726). Report is 372 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3909 +/- ## ========================================== + Coverage 44.83% 45.13% +0.29% ========================================== Files 265 308 +43 Lines 14620 21753 +7133 ========================================== + Hits 6555 9818 +3263 - Misses 7313 10875 +3562 - Partials 752 1060 +308 ```

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[Wondertan]

We need to discuss this before merging