Skip e2e test for previous implementation of slasher

[farazdagi]

What type of PR is this?

Other / Cleanup

What does this PR do? Why is it needed?

• After discussion with Raul, we've concluded that the current e2e test for slasher should be skipped:
  • the implementation is to be replaced by the new in-beacon slasher developed in feature/slasher and to be released soon.
  • current test is flaky

Which issues(s) does this PR fix?

N/A

Other notes for review

[codecov]

Codecov Report

Merging #8693 (78018a3) into develop (28e4a3b) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop    #8693   +/-   ##
========================================
  Coverage    61.15%   61.16%           
========================================
  Files          498      498           
  Lines        34711    34713    +2     
========================================
+ Hits         21227    21231    +4     
+ Misses       10332    10327    -5     
- Partials      3152     3155    +3