The OCI DNS plugin cached the tenancy, user, region and signing key into
acme.sh's account.conf at issuance and then, on subsequent runs, read those
cached values before consulting ~/.oci/config. A value cached at issuance
therefore permanently shadowed the config file, so editing ~/.oci/config
afterwards (most visibly rotating the API signing key) had no effect and
renewals kept using stale credentials, failing authentication.
Resolve each field in the order: explicit environment variable, then
~/.oci/config when it exists, then the cached account.conf value as a
fallback for env-only installs that have no config file. The signing key
likewise prefers the key_file resolved from the environment or ~/.oci/config
over any cached key.
Signed-off-by: Avi Miller <me@dje.li>
