scripts: Provide bisection_context data as argument to execute_bisection script

Currently the script assumes that bisection context file path is set as an environment variable in .env file at the beginning of pipeline. However, the contents of .env is overwritten in build_local_kernel script, when kernel build paths & Git SHA env variables are set. To avoid this, pass bisection CONTEXT_FILE path as input argument to the execute_bisection script instead of setting it in .env file.

Signed-off-by: Aishwarya Rambhadran aishwarya.rambhadran@arm.com