IN-559: optimise bam searching

[JasonLing95]

Change

• narrowing .describe return field
• print execution time after each find bam run

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This change is 

[pep8speaks]

Hello @JasonLing95! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file cron/find_dx_data.py:

Line 314:45: W605 invalid escape sequence '\Z' Line 417:1: W293 blank line contains whitespace