fix(lb): check private network status

[Monitob]

• Add check on load balancer private network attachement status
• Add context on missing queries
• Update Test
• Update Cassettes
• Update LB documentation
  Related to broken Load balancer - private network binding reported as healthy #1209

[codecov-commenter]

Codecov Report

Merging #1259 (b113364) into master (5bba67b) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##           master   #1259      +/-   ##
=========================================
- Coverage    1.44%   1.44%   -0.01%     
=========================================
  Files         102     102              
  Lines       16220   16250      +30     
=========================================
  Hits          235     235              
- Misses      15962   15992      +30     
  Partials       23      23              

Impacted Files	Coverage Δ
scaleway/helpers_lb.go	6.59% <0.00%> (-0.45%)	⬇️
scaleway/resource_lb.go	0.00% <0.00%> (ø)

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