added gRPC DNS balancing test

[asmyasnikov]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Other information

[github-actions]

github.com/ydb-platform/ydb-go-sdk/v3/balancers

compatible changes

NoDiscovery: added

summary

Base version: v3.105.3-0.20250403160823-d58c87cde674 (master)
Cannot suggest a release version.
Can only suggest a release version when compared against the most recent version of this major: v3.105.2.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.25%. Comparing base (76e62d9) to head (cd7c3b2).
Report is 1 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (76e62d9) and HEAD (cd7c3b2). Click for more details.

HEAD has 22 uploads less than BASE

Flag	BASE (76e62d9)	HEAD (cd7c3b2)
unit	6	0
go-1.24.x	9	5
ubuntu	13	10
macOS	2	0
go-1.21.x	8	5
windows	2	0
experiment	1	0
ydb-nightly	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #1722       +/-   ##
===========================================
- Coverage   71.46%   54.25%   -17.22%     
===========================================
  Files         383      373       -10     
  Lines       39895    38353     -1542     
===========================================
- Hits        28512    20808     -7704     
- Misses      10236    16290     +6054     
- Partials     1147     1255      +108     

Flag	Coverage Δ
experiment	?
go-1.21.x	53.52% <100.00%> (-17.61%)	⬇️
go-1.24.x	54.21% <100.00%> (-17.16%)	⬇️
integration	54.25% <100.00%> (-0.03%)	⬇️
macOS	?
ubuntu	54.25% <100.00%> (-17.22%)	⬇️
unit	?
windows	?
ydb-24.1	51.58% <100.00%> (-0.33%)	⬇️
ydb-24.2	51.80% <100.00%> (+0.06%)	⬆️
ydb-24.3	52.56% <100.00%> (+0.20%)	⬆️
ydb-24.4	52.45% <100.00%> (+0.23%)	⬆️
ydb-25.1	53.81% <100.00%> (-0.33%)	⬇️
ydb-nightly	?

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