LU-16502 lutf: remove lutf_start.sh wrapper script

LU-16502 lutf: remove lutf_start.sh wrapper script

Remove bash wrapper script lutf_start.sh. Set the environment
natively in Python. LUTF currently involves a number of nested
wrapper scripts. Hence, this patch aims to simplify LUTF.

It also makes it simplier to import this script into another
Python script, by providing a reusable function to set the
environment natively.

Test-Parameters: @lnet
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I56d80c12f9e50f3f8de1668ffa04c855a9829601
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53237
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Cyril Bordage <cbordage@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>