auth: Remove "shared" aka "global" secrets.

appengine/gaeauth/server/db.go

Index: appengine/gaeauth/server/db.go
diff --git a/appengine/gaeauth/server/db.go b/appengine/gaeauth/server/db.go
index 926b201c9618d07948de5ed3bb22c1a20e7e1af8..1440ed8d8bc42986c5772f8b62046dd57bd08dd8 100644
--- a/appengine/gaeauth/server/db.go
+++ b/appengine/gaeauth/server/db.go
@@ -17,7 +17,6 @@ import (
 	"github.com/luci/luci-go/server/auth/authdb"
 	"github.com/luci/luci-go/server/auth/identity"
 	"github.com/luci/luci-go/server/auth/signing"
-	"github.com/luci/luci-go/server/secrets"
 )
 
 // errNotConfigured is returned on real GAE if auth service URL is not set.
@@ -98,10 +97,6 @@ func (devServerDB) IsMember(c context.Context, id identity.Identity, groups ...s
 	return id.Kind() != identity.Anonymous, nil
 }
 
-func (devServerDB) SharedSecrets(c context.Context) (secrets.Store, error) {
-	return nil, errNotConfigured
-}
-
 func (devServerDB) GetCertificates(c context.Context, id identity.Identity) (*signing.PublicCertificates, error) {
 	return nil, errNotConfigured
 }