fix: preserve script output lacking a final newline

[priyanshurav]

Problem

If the script output did not end with a newline, then the last line that was printed to the console would get deleted,
This was due to the #clearSpinner method in Progress class deleting an entire line, just to erase the spinner.

Solution

Used control characters to only erase the single spinner character and not the entire line.

References

Fixes #8583

[wraithgar]

The efforts for this are ongoing in #8322 and waiting on some cleanup in proc-log first.