Tezt: Dal_node: Add low stake traps test

What

Adds a tezt integration test for the DAL node / baker DAL worker test_dal_low_stake_attester_attestable_slots.

Why

To increase confidence that no bugs were introduced with the !19880 (merged) effort.

How

By creating an account which acts for both the producer and the attester, with small stake, such that there is a good change that we get a Not_in_committee event. We set the traps_fraction high enough to have a good change to get traps, as well. The test runs until we get all the following events:

• Not_in_committee -> in which case there should not be any DAL attestation on the chain from that delegate at that attestation_level
• Attestable_slot -> in which case there should be Some 1
• Trap -> in which case there should be Some 0

Manually testing the MR

dune exec tezt/tests/main.exe -- --file dal.ml --title "Alpha: Testing DAL node (low stake attester attests (with traps))" --verbose

I tested this on master and on the branch that introduces the baker modifications to use the monitoring get_dal_attestable_slots RPC instead of the static one: !19880 (merged)

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR