Add catalog null check to fix initializing a MSSQL db issue

[MalloD12]

Impact

• Bug fix (non-breaking change which fixes expected existing functionality)
• Enhancement/New feature (adds functionality without impacting existing logic)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

A null check has been added in order to avoid having issues when trying to run a Liquibase command like "generateChangeLog" proving only the defaultSchemaName.

Fixes #3181

Things to be aware of

• nothing

Things to worry about

• nothing

Additional Context

• nothing

[github-actions]

Unit Test Results

  4 620 files  ±0    4 620 suites  ±0   32m 0s ⏱️ - 4m 17s
  4 619 tests ±0    4 404 ✔️ +4     215 💤  - 4  0 ❌ ±0 
54 600 runs  ±0  49 580 ✔️ +4  5 020 💤  - 4  0 ❌ ±0 

Results for commit cd154e3. ± Comparison against base commit 4c08102.

♻️ This comment has been updated with latest results.

[nvoxland]

Changes look good now, thanks @MalloD12

[FBurguer]

This PR looks good, I tried connecting to db with defaultSchemaName param with liquibase 4.16.1 and this build with the same credentials, 4.16.1 failed with [Failed SQL: (156) USE null] and this build could conect without any aparent issues.