test: fix SAML integration tests (#11241)

# Which Problems Are Solved

Some SAML integration tests used a hardcoded certificate, which expired
on the 25th December 2025.

# How the Problems Are Solved

Added helper functions to the integration package to create and store a
private key and certificate for SAML, which can be used in SAML SP/IDP
integration tests.

# Additional Changes

none

# Additional Context

- noted on #11196
- requires backport to at least v4.x

internal/api/idp/integration_test/idp_test.go

@@ -4,7 +4,6 @@ package idp_test
 
 import (
 	"context"
-	"crypto"
 	"crypto/x509"
 	"encoding/base64"
 	"encoding/pem"
@@ -459,62 +458,6 @@ func TestServer_SAMLACS(t *testing.T) {
 	}
 }
 
-var key = func() crypto.PrivateKey {
-	b, _ := pem.Decode([]byte(`-----BEGIN RSA PRIVATE KEY-----
-MIIEpAIBAAKCAQEA0OhbMuizgtbFOfwbK7aURuXhZx6VRuAs3nNibiuifwCGz6u9
-yy7bOR0P+zqN0YkjxaokqFgra7rXKCdeABmoLqCC0U+cGmLNwPOOA0PaD5q5xKhQ
-4Me3rt/R9C4Ca6k3/OnkxnKwnogcsmdgs2l8liT3qVHP04Oc7Uymq2v09bGb6nPu
-fOrkXS9F6mSClxHG/q59AGOWsXK1xzIRV1eu8W2SNdyeFVU1JHiQe444xLoPul5t
-InWasKayFsPlJfWNc8EoU8COjNhfo/GovFTHVjh9oUR/gwEFVwifIHihRE0Hazn2
-EQSLaOr2LM0TsRsQroFjmwSGgI+X2bfbMTqWOQIDAQABAoIBAFWZwDTeESBdrLcT
-zHZe++cJLxE4AObn2LrWANEv5AeySYsyzjRBYObIN9IzrgTb8uJ900N/zVr5VkxH
-xUa5PKbOcowd2NMfBTw5EEnaNbILLm+coHdanrNzVu59I9TFpAFoPavrNt/e2hNo
-NMGPSdOkFi81LLl4xoadz/WR6O/7N2famM+0u7C2uBe+TrVwHyuqboYoidJDhO8M
-w4WlY9QgAUhkPyzZqrl+VfF1aDTGVf4LJgaVevfFCas8Ws6DQX5q4QdIoV6/0vXi
-B1M+aTnWjHuiIzjBMWhcYW2+I5zfwNWRXaxdlrYXRukGSdnyO+DH/FhHePJgmlkj
-NInADDkCgYEA6MEQFOFSCc/ELXYWgStsrtIlJUcsLdLBsy1ocyQa2lkVUw58TouW
-RciE6TjW9rp31pfQUnO2l6zOUC6LT9Jvlb9PSsyW+rvjtKB5PjJI6W0hjX41wEO6
-fshFELMJd9W+Ezao2AsP2hZJ8McCF8no9e00+G4xTAyxHsNI2AFTCQcCgYEA5cWZ
-JwNb4t7YeEajPt9xuYNUOQpjvQn1aGOV7KcwTx5ELP/Hzi723BxHs7GSdrLkkDmi
-Gpb+mfL4wxCt0fK0i8GFQsRn5eusyq9hLqP/bmjpHoXe/1uajFbE1fZQR+2LX05N
-3ATlKaH2hdfCJedFa4wf43+cl6Yhp6ZA0Yet1r8CgYEAwiu1j8W9G+RRA5/8/DtO
-yrUTOfsbFws4fpLGDTA0mq0whf6Soy/96C90+d9qLaC3srUpnG9eB0CpSOjbXXbv
-kdxseLkexwOR3bD2FHX8r4dUM2bzznZyEaxfOaQypN8SV5ME3l60Fbr8ajqLO288
-wlTmGM5Mn+YCqOg/T7wjGmcCgYBpzNfdl/VafOROVbBbhgXWtzsz3K3aYNiIjbp+
-MunStIwN8GUvcn6nEbqOaoiXcX4/TtpuxfJMLw4OvAJdtxUdeSmEee2heCijV6g3
-ErrOOy6EqH3rNWHvlxChuP50cFQJuYOueO6QggyCyruSOnDDuc0BM0SGq6+5g5s7
-H++S/wKBgQDIkqBtFr9UEf8d6JpkxS0RXDlhSMjkXmkQeKGFzdoJcYVFIwq8jTNB
-nJrVIGs3GcBkqGic+i7rTO1YPkquv4dUuiIn+vKZVoO6b54f+oPBXd4S0BnuEqFE
-rdKNuCZhiaE2XD9L/O9KP1fh5bfEcKwazQ23EvpJHBMm8BGC+/YZNw==
------END RSA PRIVATE KEY-----`))
-	k, _ := x509.ParsePKCS1PrivateKey(b.Bytes)
-	return k
-}()
-
-var cert = func() *x509.Certificate {
-	b, _ := pem.Decode([]byte(`-----BEGIN CERTIFICATE-----
-MIIDBzCCAe+gAwIBAgIJAPr/Mrlc8EGhMA0GCSqGSIb3DQEBBQUAMBoxGDAWBgNV
-BAMMD3d3dy5leGFtcGxlLmNvbTAeFw0xNTEyMjgxOTE5NDVaFw0yNTEyMjUxOTE5
-NDVaMBoxGDAWBgNVBAMMD3d3dy5leGFtcGxlLmNvbTCCASIwDQYJKoZIhvcNAQEB
-BQADggEPADCCAQoCggEBANDoWzLos4LWxTn8Gyu2lEbl4WcelUbgLN5zYm4ron8A
-hs+rvcsu2zkdD/s6jdGJI8WqJKhYK2u61ygnXgAZqC6ggtFPnBpizcDzjgND2g+a
-ucSoUODHt67f0fQuAmupN/zp5MZysJ6IHLJnYLNpfJYk96lRz9ODnO1Mpqtr9PWx
-m+pz7nzq5F0vRepkgpcRxv6ufQBjlrFytccyEVdXrvFtkjXcnhVVNSR4kHuOOMS6
-D7pebSJ1mrCmshbD5SX1jXPBKFPAjozYX6PxqLxUx1Y4faFEf4MBBVcInyB4oURN
-B2s59hEEi2jq9izNE7EbEK6BY5sEhoCPl9m32zE6ljkCAwEAAaNQME4wHQYDVR0O
-BBYEFB9ZklC1Ork2zl56zg08ei7ss/+iMB8GA1UdIwQYMBaAFB9ZklC1Ork2zl56
-zg08ei7ss/+iMAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEFBQADggEBAAVoTSQ5
-pAirw8OR9FZ1bRSuTDhY9uxzl/OL7lUmsv2cMNeCB3BRZqm3mFt+cwN8GsH6f3uv
-NONIhgFpTGN5LEcXQz89zJEzB+qaHqmbFpHQl/sx2B8ezNgT/882H2IH00dXESEf
-y/+1gHg2pxjGnhRBN6el/gSaDiySIMKbilDrffuvxiCfbpPN0NRRiPJhd2ay9KuL
-/RxQRl1gl9cHaWiouWWba1bSBb2ZPhv2rPMUsFo98ntkGCObDX6Y1SpkqmoTbrsb
-GFsTG2DLxnvr4GdN1BSr0Uu/KV3adj47WkXVPeMYQti/bQmxQB8tRFhrw80qakTL
-UzreO96WzlBBMtY=
------END CERTIFICATE-----`))
-	c, _ := x509.ParseCertificate(b.Bytes)
-	return c
-}()
-
 func getIDP(zitadelBaseURL string, idpIDs []string, user1, user2 string) (*saml.IdentityProvider, error) {
 	baseURL, err := url.Parse("http://localhost:8000")
 	if err != nil {
@@ -568,8 +511,8 @@ func getIDP(zitadelBaseURL string, idpIDs []string, user1, user2 string) (*saml.
 
 	idpServer, err := samlidp.New(samlidp.Options{
 		URL:         *baseURL,
-		Key:         key,
-		Certificate: cert,
+		Key:         Instance.SAMLPrivateKey(),
+		Certificate: Instance.SAMLCertificate(),
 		Store:       store,
 	})
 	if err != nil {