fix: fixed race condition in some DA tests

[mtsitrin]

1. fixed bug in da/celestia/mock/server.go
2. removed the usage of test.NewLogger(t) as it's causes some racing errors (in case go routines exists and writes to log after the test is finished)
3. changed t.Skip("TODO") to continue in da tests

PR Standards

Opening a pull request should be able to meet the following requirements

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For Author:

• Targeted PR against correct branch
• included the correct type prefix in the PR title
• Linked to Github issue with discussion and accepted design
• Targets only one github issue
• Wrote unit and integration tests
• All CI checks have passed
• Added relevant godoc comments

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For Reviewer:

• confirmed the correct type prefix in the PR title
• Reviewers assigned
• confirmed all author checklist items have been addressed

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After reviewer approval:

• In case targets main branch, PR should be squashed and merged.
• In case PR targets a release branch, PR should be rebased.

[codecov]

Codecov Report

Merging #447 (5bddcaf) into main (1bc4571) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #447   +/-   ##
=======================================
  Coverage   52.51%   52.51%           
=======================================
  Files          94       94           
  Lines       14423    14423           
=======================================
  Hits         7574     7574           
  Misses       5774     5774           
  Partials     1075     1075           

Files Changed	Coverage Δ
da/celestia/mock/server.go	50.32% <100.00%> (ø)

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