fix(net): Fix off-by-one error in DNS seed peer retries, and clarify logs

[teor2345]

Motivation

Zebra's DNS seed peer retries aren't documented or named correctly: the number of DNS attempts implied by the name doesn't match the implementation.

Closes #6393

Complex Code or Requirements

This is concurrent async code, but this PR doesn't change the number of retries.

Solution

• Change the value of the constant and the implementation of the loop to actually implement retries, not attempts
• Don't wait for the next retry if we're not actually going to retry
• Rename the constant to clarify what it does
• Split the log messages to clarify what is happening

Review

This is a routine audit fix.

Reviewer Checklist

• Will the PR name make sense to users?
  • Does it need extra CHANGELOG info? (new features, breaking changes, large changes)
• Are the PR labels correct?
• Does the code do what the ticket and PR says?
  • Does it change concurrent code, unsafe code, or consensus rules?
• How do you know it works? Does it have tests?

[arya2]

Looks good!

[codecov]

Codecov Report

Merging #6460 (8b40495) into main (a049e20) will decrease coverage by 0.14%.
The diff coverage is 22.22%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6460      +/-   ##
==========================================
- Coverage   77.92%   77.78%   -0.14%     
==========================================
  Files         304      304              
  Lines       39639    39651      +12     
==========================================
- Hits        30887    30844      -43     
- Misses       8752     8807      +55