refactor: remove redundant get_current_time component

[ghost]

Description

Simplifies the ML pipelines by removing the get_current_time component and replacing its logic with SQL. The component takes an input timestamp - if it is an empty string (or None), it returns the current time, otherwise it returns the input timestamp as-is. This PR:

• Removes the component and unit tests
• Removes references to the component in imports and E2E tests
• Adds the same logic to each ingest.sql SQL script

How has this been tested?

Successful pipeline runs with both a timestamp and an empty string as input

Tests running successfully in the Datatonic repo here

Checklist

• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have successfully run the E2E tests - [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] I have updated any relevant documentation to reflect my changes
• [x] I have assigned a reviewer and messaged them

[ghost]

thanks @felix-datatonic !

@Linchin this is ready to merge :)