### Description

In [TransportSamlInitiateSingleSignOnActionTests.java](https://github.com/elastic/elasticsearch/pull/98882/files#diff-26733d11b06442213a040cc3d5c89595300ec813bb31076874afa38ef2ad3b91),  `/api/security/v1/saml` (deprecated) should be replaced with /api/security/saml/callback

In https://github.com/elastic/kibana/blob/b33effa182bcb7c9620c5435ab252d8067732655/x-pack/plugins/security/server/routes/authentication/saml.ts#L27

/api/security/saml/callback is the correct URL,
while /api/security/v1/saml is the deprecated URL.

Related to https://github.com/elastic/cloud-on-k8s/issues/7118
x-pack/plugin/identity-provider/src/test/java/org/elasticsearch/xpack/idp/action/TransportSamlInitiateSingleSignOnActionTests.java
final UserPrivilegeResolver privilegeResolver = Mockito.mock(UserPrivilegeResolver.class);
        doAnswer(inv -> {
            assertThat(inv.getArguments(), arrayWithSize(2));
            ActionListener<UserPrivilegeResolver.UserPrivileges> listener = inv.getArgument(1);
            final UserPrivilegeResolver.UserPrivileges privileges = new UserPrivilegeResolver.UserPrivileges(
                "saml_enduser",
                true,
                Set.of(generateRandomStringArray(5, 8, false, false))
            );
            listener.onResponse(privileges);
            return null;
        }).when(privilegeResolver).resolve(nullable(ServiceProviderPrivileges.class), any());
        return new TransportSamlInitiateSingleSignOnAction(
            transportService,
            actionFilters,
            securityContext,
            idp,
            factory,
            privilegeResolver
        );
    }
    private void assertContainsAttributeWithValue(String message, String attribute, String value) {
        assertThat(message, containsString(Strings.format("""
            <saml2:Attribute FriendlyName="%s" Name="https://saml.elasticsearch.org/attributes/%s" \
            NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><saml2:AttributeValue \
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xsd:string">%s</saml2:AttributeValue>\
            </saml2:Attribute>""", attribute, attribute, value)));
    }
}