builtin/credential-cache: fix missing parameter for stub function

When not compiling the credential cache we may use a stub function for `cmd_credential_cache()`. With commit 9b1cb5070f (builtin: add a repository parameter for builtin functions, 2024-09-13), we have added a new parameter to all of those top-level `cmd_*()` functions, and did indeed adapt the non-stubbed-out `cmd_credential_cache()`. But we didn't adapt the stubbed-out variant, so the code does not compile. Fix this by adding the missing parameter. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Taylor Blau <me@ttaylorr.com>