ewaol-tests: Fix direct execution of run-*-integration-tests

We need to ensure that we don't run bats from the current user ${HOME} to
avoid permission denied error, since at some point it will `cd "$OLDPWD"`
when we already switched to ${EWAOL_TEST_ACCOUNT} via the sudo command.

Issue-Id: SCM-4394
Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Change-Id: Ibf13cb577b6dbbef6c2e6242063265fff94c8a08