Make /pkg/creds/auth.json go away

[lkingland]

Track down which test is creating /pkg/creds/auth.json and either change the effective path to a temp directory (ideal) or remove it in a defer (suboptimal).

• track down pkg/oci/testdata/test-links/absoluteLink* as well (should be 2 files, second ending with 'Windows')

[intojhanurag]

/assign