Fix use-release-file varaible

Rename "RELEASE_FILE" parameter to "USE_RELEASE_FILE" in
release-jobs. This will match the actual varaible default value
better and will not collide with the local "release_file" in
the script.

Fix "USE_RELEASE_FILE" if statement. We are now using a bool
instead of a string.

Changing the if statements to evaluate bools.

Change-Id: I9909a16487fabacc0261f6489ac81a00cbf0f965
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>