TT-12780 prevent sql pump to panic when sharding enabled and skip api id is set

[sredxny]

Description

When using SQL pump, sharding enabled and skip api id is set then the array of data in the writeData function is empty, then prevent panic when looping over the array

Related Issue

TT-12780

Motivation and Context

How This Has Been Tested

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• Make sure you are requesting to pull a topic/feature/bugfix branch (right side). If pulling from your own
  fork, don't request your master!
• Make sure you are making a pull request against the master branch (left side). Also, you should start
  your branch off our latest master.
• My change requires a change to the documentation.
  • If you've changed APIs, describe what needs to be updated in the documentation.
• I have updated the documentation accordingly.
• Modules and vendor dependencies have been updated; run go mod tidy && go mod vendor
• I have added tests to cover my changes.
• All new and existing tests passed.
• Check your code additions will not fail linting checks:
  • go fmt -s
  • go vet