Need to fix test case assumptions so they work across platforms

[jchunkins]

Currently the test case Launch bundle in test/e2e/bundle_image_test.go assumes that the opm executable used in the test is compiled for linux. If you run this test on a darwin environment, the kube job will not succeed unless you manually cross compile for linux and include the binary at bin/opm.

[exdx]

This test should not assume it should be run in a linux-only environment