adjustments and fixes to derived table script

[sheridancbio]

A number of fixes / improvements here attempting to make this script usable in our production environment.

The script still is not running successfully from pipelines5 to the genie clickhouse databases (my test case) because of network connection problems apparently.

fixes:

• added shbang
• script used to "fail" but exit with no messages, no exception, and a success error code
• added usage statement
• renamed to be more intuitively meaningful: "rebuild_derived_tables.py"
• added if __name__ == "__main__": logic so script can be directly runnable
• dropped the default locating of clickhouse.sql in the PORTAL_HOME directory (which for us is set to /data/portal-cron - not where we would put clickhouse.sql)
• added ability to set longer http timeout with CLICKHOUSE_REQUEST_TIMEOUT environment variable